I HAD BEEN TO THE CATACOMBS BEFORE, ON A guided tour for the general public. Made up of a series of medieval mines underneath the city, they are filled with the bones of centuries of Paris’s dead.

Paris had been inhabited for millennia, so understandably, by the seventeenth century all the city’s tiny churchyard cemeteries were overflowing. Some accounts told of bodies floating around the city whenever the Seine River flooded. Finally the government condemned the city’s small graveyards, dug up the bodies from the existing graves, and moved the bones to the underground caverns beneath Paris’s streets.

The Catacomb walls were lined with the bones of its ancient residents, arranged in decorative shapes like hearts, crosses, and other patterns. It was the most gruesome spectacle I had ever seen. And to think that someone would actually spend time there . . . I shuddered, unable to imagine the kind of monster that would be drawn to such a place.

“Did he say where in the Catacombs we were to go?” Jean-Baptiste asked. “The tunnels run for miles around the area.”

I shook my head.

Gaspard left the room and returned holding a large roll of parchment. “Here’s the map of the sewers and Catacombs,” he said.

“Okay,” said Jules. “If Lucien wants us to meet him in the Catacombs while he’s giving this big party, I’m guessing there is an entrance through the club he owns. Almost every basement in the neighborhood has stairs leading down to the Catacombs. One of us should watch that access point.”

“I want to go too.”

The group fell silent, and everyone gaped at me in astonishment.

“Whatever for?” Jean-Baptiste asked.

“My sister’s in danger.” My voice cracked with emotion.

Jules put his arm around me tenderly. “Kate, your sister’s not in danger. Lucien and his crew have bigger fish to catch tonight. They’ll be thinking about how to destroy us. A human will be the last thing on their minds.”

Ambrose nodded. “And no offense, Katie-Lou, but with your fighting skills you’d be more liability than asset.” He glanced at Jean-Baptiste. “However, we shouldn’t leave Vincent’s body alone if the numa knows it’s here.”

Jean-Baptiste looked at Gaspard and nodded. “I’ll stay,” Gaspard agreed, and then spread the map across a table. The group huddled in to look at it over his shoulder, everyone contributing their personal knowledge to develop the plan.

“Jeanne has dinner ready in the kitchen,” Jean-Baptiste finally said. “You should all have something to eat, or at least take something with you. You’ll need your strength to fight.”

Soberly the group filed out of the room. The entire meeting had taken less than an hour. But it was coming up on nine, and the deadline was quickly approaching.

Jules stayed behind and walked with me out of the room. “Vincent is asking me to talk to you for him, since your communication is still limited.”

I nodded.

“He says he has to go with us. We’ll need his help to locate Charles. He says he wants you to go back to your grandparents’ home to wait.”

“No,” I said stubbornly, and then said it again to the air. “No, Vincent. I’m worried sick about all of you, and Georgia, and want to be here when you get back.”

Jules listened and then said, “He agrees that you’re as safe here with Gaspard as you would be at home. But he doesn’t want you to worry about Georgia. At least, not tonight. As long as she stays at the party she’ll be safe. They would never fight us in front of hundreds of people.”

Trust me, the words ran through my mind.

“I do,” I said.

The next half hour was controlled mayhem. Jeanne put a spread of food out on the table and then disappeared down the stairs into the basement. I followed her to the gym-slash-armory and watched as she opened and closed cupboard doors. She pulled heavy instrument cases out of closets and spread them open on the floor with the same efficiency she used to take croissants out of the oven.

“What can I do to help?” I asked.

“Nothing. It’s done,” she said as she pulled out an enormous case for a double bass. It opened to show an empty shell with built-in compartments dividing its velour-lined interior into a dozen different sections. Seeing the shape and size of the weapons hanging on the walls, it wasn’t hard to guess what the case was intended for.

Charlotte was first down the stairs and began pulling weapons off the wall. Choosing a couple of swords, a dagger, some weird ninja-looking objects like throwing stars, and other things I couldn’t name if I had to, she nestled them into their slots in an electric guitar case.

Stripping down to her bra and panties, she began layering: first a long-sleeved skintight black shirt, then black leather pants tucked into tall leather boots. Jeanne helped her strap on what looked like a Kevlar vest, and then she threw a dark zip-up sweater over the ensemble. A black sleeveless fake-fur vest, with a balaclava stuffed into one pocket, finished her uniform. She looked like Attila the Hun’s right-hand woman. She looked deadly.

Her entire packing-and-changing routine took less than five minutes, and by the time she was done, Ambrose and Jules were downstairs, packing their own cases with weapons.

Ambrose had the double-bass case and was filling it with a veritable armory of battle-axes, maces, swords, and other dangerous-looking blades. Jeanne laid out the boys’ clothes and then rubbed her hands together and glanced around proudly, looking every bit like a doting grandmother sending her grandchildren off to school.

“So is this whole military setup just for going to war against the numa?” I asked Charlotte, who had come to stand next to me.

A fear had begun taking hold of my stomach, like a miniature anaconda squeezing my insides. I wasn’t afraid for Vincent, doubting that in volant form he could be hurt by Lucien and his crew. But seeing the Kevlar vests and layers of protective clothing drove home the realization that my new friends were putting themselves in mortal danger.

“Look who’s ready first. As usual,” Charlotte called mockingly to Ambrose and Jules, and then turned to answer my question. “No, Kate. This isn’t all about the numa. Saving lives doesn’t just mean jumping in front of speeding bullets or pushing suicides out of the way of trains. We’ve been on SWAT teams, acted as bodyguards, served on antiterrorist squads. . . .” She laughed at my doubtful expression. “Yes, even me. I’ve made it to seventeen before, and makeup and the right haircut add years to my age.”

Jules had strapped a crossbow and arrows into a large case and was overlaying them with daggers and swords. He looked up from his packing and, noticing my gaze, gave me a flirty wink.

“Why don’t you guys just use guns?” I asked, amazed by their casual attitude.

“We use guns when we’re expected to,” answered Charlotte, “if we’re fighting alongside humans in the cases I mentioned . . . bodyguarding and the like. But bullets don’t kill revenants”—she paused—“or others like us.”

Before I could ask her to clarify what she meant by “others,” Ambrose, lacing up some massive steel-toed boots, yelled, “Plus, Katie-Lou, you’ve got to agree . . . hand-to-hand combat is way cooler.” Despite myself, I laughed. He obviously loved a fight.

“How many times have you gone up against Lucien and his crew?” I asked.

“Uncountable. It’s all part of a never-ending battle,” Charlotte responded.

“Well, it must mean you’re winning if you’re all still around.”

No one answered. And then Jules broke the silence. “Let’s just say there used to be a lot more of us.” The snake inside me constricted so tightly I couldn’t breathe.

“There also used to be a lot more of them,” called out Jean-Baptiste, who, with Gaspard, stepped down into the room. Charlotte, Ambrose, and Jules stood up, as if at attention, while Jean-Baptiste walked back and forth among them, carrying out an inspection of their body armor and weapons cases. “We’ve got everything,” he said finally, nodding at the three of them approvingly.

He took two normal-looking canes out of an umbrella stand and threw one to Gaspard. With a lightning-quick movement, Gaspard drew a sword forth from the cane and inspected its blade.

They certainly looked like a mini army, led by a fierce general. But individually, they could pass for musicians dressed for a gig—that is, if their band had a marked penchant for leather.

They led the way through double doors at the end of the gym, and up to the back courtyard where several cars, motorcycles, and scooters were parked. Jean-Baptiste climbed into a midnight blue sedan, while Jules and Charlotte took a dark-hued 4x4. Ambrose strapped his case to an enormous Ducati and started up the bike’s engine with a roar.

As the other vehicles started their motors, I clutched my arms across my chest and clenched my teeth. This isn’t my fight, I thought, it’s theirs. But I couldn’t help feeling helpless—like the damsel in distress that I never wanted to be.

I heard Vincent say, When we’re done, I’ll come back to you.

“Be careful,” I murmured.

Nothing can happen to me, the words came. My body is here with you.

“Take care of the rest of them, then,” I said.

Good-bye, Kate, mon ange.

The cars began backing up, and smoothly exiting one by one through the gates into the dark night beyond, they were gone.