While she methodically searched the slides, she was able to multitask by trying to come up with what the specific toxin might have been. She assumed it was a neurotoxin, as she’d decided earlier, of which there were many different kinds in snakes, scorpions, aquatic mollusks, and even certain fish. With that thought in mind, she turned away from the brain slides temporarily to go online to review neurotoxins. Because she’d come to assume her two cases were people of Japanese ancestry, the one toxin that jumped into her mind was tetrodotoxin, possibly the most infamous toxin in Japan, since it was associated with multiple episodes of illnesses and deaths in unlucky sushi and sashimi lovers. The toxin came from bacteria associated with a number of creatures, including a particular puffer fish whose flesh was considered a delicacy in Japan. The problem was that the flesh could contain tetrodotoxin at particular times of the year, whereas it is usually confined to the fish’s viscera, such as its liver and skin.

Laurie focused her search on tetrodotoxin, with the idea of seeing if it could cause convulsions when administered parenterally, meaning by injection. As she skimmed several of the articles, refreshing her general knowledge of tetrodotoxin, she recalled that it was a useful compound and was used rather extensively in medical research and even in clinical medicine. In clinical medicine it was used to treat cardiac arrhythmia and also as a pain reliever in extreme situations, such as in cases of terminal cancer and debilitating migraines. She thought this was an important issue in that it meant the drug was commercially manufactured, hence readily available. There were many other neurotoxins that were quite exotic and extremely difficult to obtain.

“Yes!” Laurie suddenly said, and snapped her fingers as she read that tetrodotoxin could, when injected, cause convulsions, which wasn’t the case with the other classes of neurotoxins. Continuing on in the same article, she also was reminded of tetrodotoxin’s impressive toxicity: Two hundred-thousandths of an ounce could kill a one-hundred-and-seventy-pound person. Laurie whistled at such a figure, realizing tetrodotoxin was one hundred times more poisonous than potassium cyanide.

While marveling over tetrodotoxin’s lethality, Laurie’s eyes wandered over to the institutional clock hanging on the wall over her file cabinet. It was nearly one p.m. Knowing John DeVries would surely be back to toxicology, she grabbed the sample bottle and headed to the elevator.

When Laurie walked into John’s bright, spacious windowed corner office, which contrasted so sharply from his previous windowless cubbyhole, she could certainly understand how it could improve one’s mood. John was just donning a fresh white lab coat as she appeared at the door. His secretary had yet to return from her lunch.

For a moment Laurie just stood there, transfixed by the man’s metamorphosis. He was still tall and thin but no longer gaunt, and his former academic pallor had been replaced with a brush of color across his cheeks, making him look ten years younger.

“Ah, Miss Laurie,” he said, catching sight of her. “I’m afraid there’s been no change from this morning: no toxins or poisons or drugs.”

“Did you run another sample?”

“Well, no,” John admitted. “Not yet. We’ve been busy with a number of overdoses from last night.”

“Well, I have some news that I’ll clue you in on,” Laurie said, dropping her voice in a playful fashion. “But you’re not to tell anyone else until I have my mini-press conference later this afternoon.”

“I promise,” John said.

Laurie went on to tell John about her discovery from the security tapes that her case represented a robbery and that she had reason to believe he’d been murdered in the process with a toxin delivered with some sort of air gun. As she expected, John was immediately intrigued.

“You got all this from security tapes?” he asked. He was impressed.

“I did,” Laurie said. “With a dollop of inference. By the way, do you recall a famous assassination that happened in London involving a Bulgarian diplomat? He was killed by a toxin that was shot into him by a pellet gun hidden in an umbrella.”

“Absolutely,” John said. “It was ricin. Are you suspecting your case was a copycat?”

Laurie nodded. She was impressed not only that John remembered the case but that he’d also remembered the specific agent involved. “I believe it was a copycat, to a degree.”

“Are you then suggesting we should be looking for ricin?”

“No, I don’t think ricin was involved, because the victim convulsed, and ricin does not cause seizures. But from watching security tapes, I know one of two perpetrators was carrying an umbrella. Because the subway station was so crowded, I wasn’t able to actually see the umbrella used, but after the attack, when the victim was lying on the concrete, one of the attackers appeared to partially open the umbrella and cock it to get it to fully close. My sense is that the umbrella was some kind of air gun like the one involved in the case in London.”

“What about an entrance wound?”

“Good question,” Laurie commended. “I found one today when I redid the external exam. I’m embarrassed to tell you why I didn’t find it yesterday. There’s a small entrance wound on the back of the victim’s leg at the juncture of the leg and the gluteal mass.” Laurie held up her sample. “And this is an en bloc excision of the track, which seemed to be about an inch long.”

“Perfect,” John responded. He reached out for the bottle, held it up, and glanced in at its contents. “If the agent was not ricin, do you have any idea at all what it could have been?”

“Actually, I do,” Laurie said. “I think it might have been tetrodotoxin.”

John stopped looking in at the tissue sample and switched his attention to Laurie. “Do you have any specific reason to suspect tetrodotoxin?”

“First, I think whatever was used would have had to have been a neurotoxin,” Laurie said. “Whatever it was, it definitely caused a convulsion. It was a short convulsion but a real one, both because it was seen by the nine-one-one caller and because I saw it on the security tape. Tetrodotoxin is known to be able to cause seizures when it is injected internally. This afternoon when I looked into neurotoxins, I didn’t notice any others associated with convulsions. Second of all, the stuff is manufactured on a regular basis, so it’s available. And third of all, and this is the least scientific, but I believe my patient is Japanese, and Japanese have a long history with the toxin, thanks to puffer fish.”

“Sounds promising,” John agreed with a laugh. “All except the last part.”

“Now for the ninety-nine-dollar question,” Laurie said. “When can we run it?”

“Why am I not surprised,” John said, humorously throwing up his hands in mock despair. “I suppose you want it ASAP, like tomorrow, as if you are the only ME in this organization and we are sitting around up here, twiddling our fingers.”

“I’d love to have it today,” Laurie said with a smile. “It would be my coup de grace for this afternoon revelation.”

John threw back his head and laughed. “I suppose I never can please you. You’re always in such a hurry. But tell me, you used the pronoun ‘we’ when you asked when it could be run. Was that a literal we or a figurative we?”

“Literal,” Laurie said without hesitation. “I was pretty handy around the lab in college and in biochem in medical school. If one of your techs or yourself could throw me some hints now and then, I believe I could muddle through it. As soon as I finish the rest of the case’s histology slides, I have a free afternoon.”

John regarded Laurie for a beat, wondering if it was a good idea to let an amateur loose in his lab or a recipe for disaster. In favor of allowing her to work there for the afternoon was that he liked her and respected her enthusiasm and dedication, and the fact that she had always appreciated his work and had frequently told him so.

“Have you ever used an HPLC/MS/MS, otherwise known as a high-performance liquid chromatography with tandem mass spectrometry unit, before?”

“I have,” Laurie said. “During my residency training I spent some time in the lab as an elective.”

“Also, we’ll need some actual tetrodotoxin, which I don’t have here, but they’ll have next door at New York Hospital.”

“I’ll be happy to run next door to get it.”

“All right, why not?” John said with sudden resolve. “I tell you what we’ll do. I’ll have one of my techs start by using a sonicator to turn some of this tissue sample into organic slurry. When you come back, I’ll let you do the extraction with either n-butanol or acetic acid. I’m not sure which, but I’ll decide by the time you get back. Sound okay?”

“Sounds perfect,” Laurie said, flashing John a thumbs-up sign before spinning on her heels to head back to her office. She now had true motivation to finish up with the histology slides.