“One day, here in the tunnels, I met a man, a traveler passing through. He was homeless and eager for conversation from one who was unafraid and willing to engage with him, as I was. When he mentioned he was a twin, I knew my chance had come. I took him deep within the catacombs, into one of the many rooms, and performed my first experiments on a live subject, testing his blood, his muscle tissue, and taking these samples to the hospital lab before I had proper equipment moved here. I knew no one would come looking for him.”

Cold fear spiders across my skin, hearing the preview of what’s in store for us. I lick my lips and try to discreetly scan the room for a weapon. I’m not chained up yet, like Angela.

“I was clumsy, at first,” Seb continues, nodding at this disappointment. “I gave too much anesthesia during procedures to make them more bearable, but I soon learned that progress will not allow for anything but precision.” He purses his lips. As if he regrets withholding the one thing that could be considered a mercy.

“How many bodies did you need before becoming . . . practiced?” The cabinet of tools with its sharp and shiny objects is off in the corner, another twenty feet away and behind Seb. Out of reach.

“Too many. You’ll recall studies show infant twins can sense when their sibling is in distress? At first, I focused on individual, fraternal twins, hoping to leverage this ability, before realizing—” He locks eyes with me. “I needed a complete set. From there, I theorized that twin abilities must be heightened among identical twins.”

All those people. The four bodies before I arrived, and the three after. “You’re the serial killer the police are looking for,” I say on an exhale.

Seb straightens, stands up tall. “I will thank you not to trivialize my work, Shayna. Each contributor—the two homeless men, the carpenter, the woman I located through my access to records at the hospital, and the gypsy girl—took me another step toward finding a cure.”

“Why did you kill Leroux? Was he a twin?” It seems years ago that I watched Valentin exit a building with scissors and thought he had taken something from the crime scene, like a serial killer would do. In hindsight, the pair of scissors was marked with masking tape, likely police property used to cut through Leroux’s clothing or remove his zip ties.

A sob bursts from Angela; she didn’t know, hiding underground, dashing out above for food and to leave me notes, that her internship director had been killed.