“She isn’t the first,” Oldmark said to me.

“So you said in your letter.” That’s why they’d come to me, after all, and I had to confess it was flattering. It’s not easy building up a reputation in a city as big as London, crammed with weather-readers, wind-listeners, earth-healers. And river-speakers. Not easy, especially if you are a woman, and young.

You’d think having a queen on the throne, in this year of our Lady Sixteen Hundred and Two, would make a difference. But then again, Aeve wasn’t entirely human, and perhaps that made a greater one.

“You see, Mistress Dane—” Oldmark broke off. For a courtier, he seemed to have some difficulty in expressing himself.

“You may call me Mistress Isis, if you wish. We’re to be working together, after all. And I’ve seen the drowned before, you know. Part of my job is to find the bodies of those who have been unfortunate enough to meet their deaths in the river.”

“I suppose you work principally with the Thames?”

“Yes, but also with the Wye, the Tyne . . . And I grew up on the banks of the Severn, near the Welsh border at Lydd’s Ney. That was where I first found I could river-read.”

“Do you think this is to do with the Thames?” Oldmark asked. The woman was gliding through the wall. A moist stain showed briefly in her wake, and then there was nothing.

“I’m not sure.” Some mages pretend to know everything, all bombast and certainty, even if they couldn’t tell you whether it was day or night. This would not, I knew, be the right tack to take at Aeve’s court: the queen had half-faery blood, could smell out a lie as easily as if it were a rat under the floorboards. She hadn’t kept her throne for ninety years for nothing. It was hard to explain to Oldmark, but this did not feel like the genius loci of the Thames: Thamesis, that bearded, weedy, silty presence, a spirit old when the first hunters had come to his shores, before history began.

“Can you find out?”

“I believe so. Tell me, Lord Oldmark, what is the lowest point of Coldgate?”

Oldmark thought for a moment. “It would be the cellars, where we keep the ale. They say the foundations date from the days of the Romans. I do not know whether that is true, but certainly there are a great many steps leading down to the cellar . . .”

“Please take me there, Lord Oldmark, and I will see what is to be seen.”

He was right about the steps. I counted forty, leading in an arc down into the musty depths of the cellar. The floor was made of flags, a glossy gray stone. The cellar smelled of wine, of moss, of rivers. Oldmark left me in a small pool of light cast by a candle; when he had gone, I blew the candle out and stood alone in the dark.

At once, the drowned were all around me, sensing my presence as they might sense the spirit of water. I felt a chill breath on my face. Damp fingers trailed through my hair.

“Hush now,” I said, softly so as not to frighten them. “I don’t mean you harm.” The spirits of the water-dead are rarely hostile, tending rather to a fluid sadness, and they must be treated gently.

One of the spirits floated into view, releasing her own phosphorescence, a green-pale glow. A girl, only a little younger than myself, with a purple mark around one eye.

“Who are you?” I asked. I put ritual weight behind my words, speaking in the Tongue of Water rather than my native English. “Why are you here?”

At the sound of the Tongue, her face grew still and slack, and I felt a little guilt at that. “My name is Sarah Mew. I was told to go with the others and wait for the boat.”

“Which boat is that, Sarah?” Had she been left on the shore, been taken by the waves? But she answered, “The boat that is coming. The one that leads the fleet.”

“Sarah, you must tell me what you mean. Which fleet?” It struck me that, for all her mention of the future, she might still have been speaking of the past: one of the interminable skirmishes with the Spanish navy off the shores of Albion, for instance.

“The fleet that is coming,” she whispered. Her drowned face contorted with the effort of speech: she was enspelled, I saw, and my own magic was trying to counter that which had been placed upon her. And that other magic was stronger. I felt it sweep through the cellar like a tide, washing her away. She spun through the dark air and through the wall, no more than flotsam, and was gone. I was alone in the cold chamber.

I went slowly back up the stairs and found Oldmark. He was standing disconsolately by a window, staring out at the rain streaking down the leaded panes.

“Mistress Dane! Is everything well?”

“I am well, Lord Oldmark, but I’m afraid that I have some bad news. I have spoken with the drowned. They tell me of a fleet that is coming, a fleet of ships, and from the magic that was placed upon the spirit with whom I spoke, we face considerable danger. This was not an ordinary spell. It swept my magic away; only now is it beginning to creep back.” This was true. I could feel it starting to seep into my soul again, refreshing its parched ground.

Oldmark blanched. “Danger! From which quarter?” “I could not say.” This, on the other hand, was not true. In that moment when the tide had caught the spirit in its grasp, I’d sensed something distinctive, familiar—a mossy greenness, a sudden dank and earthy taste in the air. The magic of Aeve’s cousin and mortal enemy, the Queen-under-the-Hill.

Faery magic, then. No surprises there. But Aeve would not be pleased.

The queen wanted me to find out more about the fleet. This time, she spoke to me herself. I was granted audience in the great hall of Coldgate, myself on bended knee, head bowed, Oldmark fidgeting off to one side, and the queen—in the quick glimpses I got of her—sitting upright on the carved stone throne, her skin the whiteness of the stone itself, lending her a statue’s look. Her hair was the pure blood-red of faery, her gaze a slanted green. She did not look to be a hundred years old, but then, in terms of her own family, she was little more than a girl.

“You look afraid,” she said, when I hesitated in the course of my explanation. “Are you?”

I saw no reason to lie. “Yes,” I told her. “I am afraid of the magic of under-hill.” Of your relatives. Old magic, root-and-briar magic, coiling and twining and dragging you down into earth and dreams . . . I’d chosen the river rush, after all, or been chosen by it. I wanted something clear and clean.

“You are wise, then,” Queen Aeve said. “Tell me. Can you find out more, or are you too afraid?”

“I am afraid, but I will do as you ask.”

I felt, rather than saw, her smile.

“You’ll be rewarded,” was all that she said, but she did not say how.

If you want knowledge, of magic as well as rivers, you need to go to the source. The Thames rises near Oxford, the city where my mother was born, and in its early stages it is called the Isis: hence, my name. I took my mare from the royal stables at dawn the next day and rode west, setting a hard pace across the chalk hills and the beech groves, until we saw cream-gold towers in the distance and Oxford lay before us.

They’d let me study here, a great favor, since I am a woman. Not officially, of course, but sub rosa, lessons taken in a shadowy cell at the back of the Bodleian library. I had been granted this as a result of my grandfather, cleric and scholar, endower of a college that was already three hundred years old. I had learned a great deal about rivers, about the sea, in this land-locked, placid city in the middle of the wheat-pale hills.

Now I skirted the city bounds, stopped at an inn overnight, and continued west until I came to a stone by the side of the road that showed the way to Seven Springs. The grotto lies high at the Cotswold edge, river-birth carving limestone into palaces and caverns. When I arrived, early on the morning of the second day, there was no one there. A light mist was spiraling up through the branches. Beech mast and acorns crackled under my boots, and the cave-mouth lay before me, so enveloped in the white exposed roots of the beech that it was hard to tell where wood ended and stone began.

I was glad to be alone, but it also made me afraid. Not good, I thought, to be up here in the hills, the kingdom of faery. The goddess would protect me, or so I believed, but who ever really knew? I remembered walking along the Severn shore, looking westward to the black line of the Queen’s Forest and beyond that the dusk-blue hills of Wales and the line of fortress castles, magic-warded. The court of the Queen-under-the-Hill lay behind that iron band. Aeve’s cousin, Aeve’s rival, and a long enmity between the two thrones of Albion, one dark, one—or so Aeve claimed—the province of the Light.

Sometimes even a dim light can illuminate, if the shadows are dark enough.

Time to face my own darkness. I lit a candle and stepped inside. Water-breath, and presence: not the green deep presence of Thamesis himself, but the Riverine Isis, delicate, a cat-soft whisper in the shadows.

“My Lady?” No reply, but I didn’t expect one, not straight away.

I walked deeper into the temple, as far as the first spring, and held the candle out over black water. I could see my own face reflected in the dark mirror of its depths: I did not look like myself, but older, the woman I would one day be. And behind that, overlaid, was another face that was not myself at all.

Reflected flame flickered. I said, “I spoke to a ghost, and she told me of a fleet. There was magic in it, from Under-Hill. I need to know where the fleet will come from.”

No answer. I stared into wet fire, beginning to think that this, too, would be withheld. Then the lips of my reflection moved, although I myself had finished speaking.

“Watch for the Lowlander,” the reflection said. “Watch for the midnight moon.”

“Who is the Lowlander?” I asked, though I thought I already knew: the Dutch considered that they had a claim to the throne of Albion; there had been incursions, and almost certainly there were spies.

The face was silent and still. A ripple of water, caused by a breeze that I did not feel on my skin, eddied across the surface of the black pool. The chamber grew colder; I was gazing back at myself alone. Though the candle still flickered in my hand, in the water, the flame was no longer to be seen.

I made an offering of cyclamen to the wall shrine, placing the white flowers before the black face of the Riverine Isis, and walked out into the day. The sun was rising, gilding the mist and causing the trees to drip. An insubstantial landscape, luminous, half-real. I rode back to London, thinking of the Dutch.

The queen was of the same mind as myself, Oldmark told me. A Holland spy had been arrested in the grounds of Lydgate Palace only a week before. There had been a diplomatic incident, only half-resolved, and the Dutch court was threatening to raise penalties on shipping.

“It would not surprise anyone,” Oldmark said, “to learn that there is mischief afoot in that quarter.”

“But why involve the dead?” I asked. “And why was there under-hill magic present?”

Oldmark looked uneasy. “I do not know. But an alliance between the Lowlands and Under-Hill would be a sorry thing. There have already been rumors that the Queen-under-the-Hill courts the Spanish, and you know that there are political connections.”

I did know; I nodded. “I wish I’d been able to find out more,” I said.

“I am certain that you did your best,” Oldmark replied.

But that night, the drowned came over-ground.

I was roused from my sleep by distant shouts. The sound was coming from the direction of the palace gardens. Accommodated in the servants’ wing as I was, it took me a little time to throw on a robe and make my way through a maze of passages to the front of the building.

They were coming out of one of the fountains, an endless procession of white-faced, green-haired spirits. Some of them were decomposing away, just as their bodies had done: These were the ghosts of those who had lain long in the water, so long that it had seeped into their souls to rot and stain.

Oldmark appeared beside me, almost as white faced as one of the spirits.

“What are they doing?” he whispered.

“I don’t know.” The procession of ghosts was heading toward the water-stair, the gates that led down to Thamesis. Toward and then through, disappearing into—it must be—the river. Gesturing for Oldmark to stay where he was, I opened the French doors and ran down the steps to where the ghosts walked.

Sometimes they can’t see you. To them, you are as vague and shadowy as they are to you, and perhaps as terrifying. But when I put out a hand, with the fluttering of a spell, one of the spirits turned his head.

A man in a costume I did not recognize: rough trousers and a dull tunic. Long hair straggled down his shoulders, twined with weed. Not a recent ghost, then. He spoke to me, and I did not know the language, either: something Northern and harsh. I looked over his shoulder to his fellow spirits and saw a woman in a long, draped dress, her aquiline features downcast and somber. These were ghosts from the far past of Albion, and so many of them: summoned from every well and river and spring, every shore. The reek of under-hill magic hung about them. I looked back to Coldgate and saw the gleam of gold beside Lord Oldmark. The queen had arrived.

The stream of ghosts was slowing, and soon no more crawled out of the depths of the fountain. I went slowly back into the palace.

“I have sent word to my cousin Under-Hill,” Queen Aeve said. I began to curtsey but she waved me up again. “I have told her that I know of her plot with the Dutch court, that I will not tolerate it.”

Lord Oldmark and I waited; neither of us wanted to be the one who asked her what she planned to do. But she went on, “I’ve ordered the fleet of Albion to the mouth of the Thames, to sail for Dutch waters.” Her face twisted. “We have made mincemeat of the Spanish. Let the Dutch see if they have better luck, shall we? Oldmark, see that Mistress Dane is paid.” With that, she swept back into the palace.

One does not question the actions of a queen, at least, not out loud. But Aeve was ever one for the grand gesture. Sending the navy to chastise the Dutch, on what was still little enough evidence, was characteristic. And the navy, though still great, was not what it had been when Aeve first came to the throne, before its flagship, the Rose, had gone down under Spanish guns, taking Albion’s Admiral Drake with her.

Oldmark turned apologetically to me, disturbing my speculations.

“Mistress Isis, I know the queen appreciates your help.”

“I have helped little enough,” I said. I was not being modest. In fact, although I did not say so, I felt that I had helped only in setting Queen Aeve off upon the wrong track, a hound after a false scent. I did not say that, either—it is not safe to compare queens to bitches.

“Lord Oldmark, might I remain in that chamber for a night or two more, before returning to Gloucestershire? There is an avenue of research that I should like to pursue.”

Oldmark appeared slightly surprised, but he agreed. I returned to my room and took out the small traveling chest, setting it upon the table.

Inside the chest were the characteristic accoutrements of the river-speaker: the forked hazel twig, bound in brass, the lead and crystal compass, a collection of maps. I took the maps out of their leather case and riffled through them. I wanted to see where Coldgate lay.

London is a river city. Everyone thinks only of the Thames, but the streets are built over rivers, hidden streams, concealed rivulets. The Wandle, the Effra, the Westbourne and the Fleet; the Falcon, the Ravensbourne, the Earl’s Sluice, and many more. All the drowned streams that flow beneath the city to the Thames.

I was right. I’d felt it in the wine cellar, that breath of dampness, a river’s ghost. The oldest map of all showed a stream running underneath Coldgate. It had been known as the Winterbourne, and at this, my heart stuttered a little, for the bournes have a magic all their own. Underground streams, which can be summoned to rise again in times of great peril.

Or in times of war.

At that moment, I thought I knew what the Queen-under-the-Hill might be trying to do.

I picked up a cloak and the hazel twig and went out into the evening. A fog had come up from the Thames and hung over the box hedges, playing around the fountain in watery coils of its own. Late November and the taste of mist in the mouth . . . Water rising, in times of war. When I reached the fountain, I held out the hazel twig. A moment, and then it twitched. From the map, the Winterbourne lay beneath. I followed it back to the wall of Coldgate, hastened back down into the cellars.

It took a lot of searching before I found the little door, hidden and dusty behind a stack of barrels. It had once been locked, but the lock was rusted, and I pulled it away. It was unlikely that what lay behind it had been deliberately concealed—the lock was there to prevent people from wandering down beneath the cellar. Steps led down, and I followed them.

I did not get far. The smell of water struck me halfway down the slippery stair, and then it was all around me—I clung to the rail, in a minute of sheer panic during which I thought I would be swept away—but it was not real. The ghost of the Winterbourne was rising, spectral water all around me. My lamp showed diffuse and dim, rocking my hand, and around it I glimpsed a shoal of eels, tails flicking as they sped along. Standing in the race of the water I felt like a ghost myself. I backed up the steps and looked down into the foaming torrent.

It wasn’t just the spirit of the river that was rising. Magic was rising, too. It was all around me, tugging, curious, and I did not want to be noticed in this way. I slammed the door to the wine cellar shut with a muttered spell and went to tell Lord Oldmark to get me a boat.

Thamesside, looking back at Coldgate. We rocked on an icy current, the river slapping our little boat back and forth. Behind us, heading for Tower Bridge, one of the huge coal barges churned slowly downriver, the horse-team on the opposite bank patiently padding along toward the eastside docks.

“You had best be correct in this, Mistress Dane,” the seated figure at the prow said. Aeve’s voice was river-cold.

“Your Majesty, if I am not, my reputation is in any case gone, and I do not care what happens then.”

The queen inclined her cowled head.

“The navy has been ordered to continue out into the North Sea,” Oldmark said to me, in a low voice. “All but five ships, which are heading back to London.”

“Even the navy will not be of much help, if I am right. Aeve must appeal to Thamesis, as rightful ruler of the river’s city.”

Oldmark nodded. “You have explained. She knows what she needs to do, if it comes to that.”

It will, I did not say. I was sure that I was right, but arrogance is best left undisplayed. “Watch the palace,” I told him.

I could sense it in the air, magic building up, as if behind a dam, with the strong mossy taste of Under-Hill. “It won’t be long,” I said, beneath my breath. Aeve turned, irritably, with the impatience of queens.

“Nothing is happening.”

I couldn’t really blame her for the irritability: It was foggy and freezing out here in the middle of the river. I was surprised that she’d agreed to come at all. And as if prompted by my thought, the queen came to a decision.

“We will go back,” Aeve said and rose.

“Wait,” I said, forgetting to address her as I should, but as I spoke, Oldmark echoed me, “My Lady, wait.”

Before us, across the black, choppy expanse of the river, Coldgate was fading. Magic was humming in the air like a beehive, so strongly that my skin prickled and burned. Aeve gasped as it struck her. Instead of the palace, its grounds, the streets that lay beyond its walls, we were facing the mouth of the now-buried Winterbourne, a ghost shore, muddy and strewn with stones. A single post rose up from the mud, tapered to a point and covered with weed: some ancient marker from the time before the Romans came to London. It shimmered, and I saw the skull that crowned it, grinning.

Aeve put out a hand, as if touching enemy magic.

“Your Majesty, be careful—” I started to say, but Aeve was already beginning the incantation I had given her, her own power rising now, the authority of the rightful ruler of Albion, calling upon her ancestors, summoning up the protection of the dead.

It was protection that was needed. A ship was coming down the mouth of the Winterbourne, a galleon with tattered sails, sides so encrusted with barnacles and shells that the ship looked more like some dredged wreck than a proper vessel. I saw the pilot standing at the wheel, a white face beneath a tricorner hat. The Lowlander. The Dutchman. And a ship that would sail the seas forever, unless someone not human offered another choice, an unrefusable bargain.

They say the Dutchman ruled the seas beyond death and all who sailed upon them . . . Behind his ship came others: Spanish flags flying, French, a longship with a boar’s crest. Dozens of ships, all those that had gone down in the seas off the coast of Albion, the wraiths of enemy vessels, conjured by the Queen-under-the-Hill.

“Queen Aeve!” I shouted, above the sudden roar of magic and dead water. “Call on the Thames!”

And she did. She used incantations that blazed through me like flame, words that I, not of royal lineage, should not have heard, spells that are in the blood and bone of Albion’s ruling house. Oldmark was crouched on the floor of the rocking boat, his hands clasped to his ears. I nearly joined him.

Then a wind stirred my hair, and I turned. The prow of a ship arched above us, an immense thing, far larger than it had been in life. Its sails billowed out, lit by a light that I could not see, as though it were catching the last rays of the sun. I had never set eyes on this ship before, and yet I knew it: the lost Rose, with Admiral Drake standing at the wheel.

I seized an oar. “Oldmark! Set to rowing! We have to get out of the way.”

Aeve was still in the prow of the rowing boat, arms outstretched, calling magic in. I didn’t want to be responsible for pitching the Queen of Albion overboard into her own river, but I didn’t want to be run down by even a spectral ship, either. Frantically, Oldmark and I hauled the boat around as the Rose glided forward.

The Dutchman’s ship turned, wheeling on a tide that wasn’t there. I saw the guns of the Rose blossom silently over my head and a watery fire erupt from the sides of the Dutchman’s ship. There was the flame of a cannon behind the Dutchman’s vessel; the Rose gave a great shudder, as if struck.

“Mistress Dane!” Oldmark cried. “Turn her! Turn her now!”

But we were too late. The Rose glided forward and through us, sleek as a swan. Everything went black for a moment—it’s not pleasant, being run down by a ghostly galleon. My bones rang and my teeth chattered. When I could see again, the Rose was bearing down on the Dutchman’s ship, and the magic that had drawn the ghost of the Winterbourne upward was congealing, drawing around the Dutchman’s vessel to imbue it with power. Coldgate was once more visible through the shimmer of the river. The guns blazed again from the Rose, and this time I heard them. The Dutchman’s ship gave a groaning creak and listed. We huddled in the rowing boat, Aeve damp-browed and shaking, and watched the Dutchman’s ship go down.

It sank, stone-swift, as if the Thames had swallowed it. With it went the magic of Under-Hill, sucked into its wake, but the Winterbourne did not go too. Instead, I saw the course of the river turn and shift, sweeping away the post with the skull and all the spectral ships, carrying them out into the wide channel of the Thames and away toward the sea. At last the river was also gone, a foaming tide, and Coldgate loomed pale through the river mist. When the fog parted a little, I looked for the Rose, but it was no longer there.

Aeve proved more generous than I had expected, but then, I had saved her throne for her. I rode back to Gloucestershire and Severnside on a chilly November morning, a moneybag heavy against the flank of the mare. I felt drained, the wonder of what I had seen sitting within me as heavily as my reward, and I was thankful to see the Severn curling between its red-earth banks, with the blue hills of Wales rising beyond.

But I did not think I would be visiting those hills in the months to come, for fear of what lay beneath them. I set my heels to the sides of the mare and rode hard for home, along the river shore.