Something bit into my skin.

I looked down, stupidly. My hands were so cut up and bandaged that I could hardly tell what had happened. There. A pinprick of blood near the knuckle of my index finger.

I didn’t think anything of it. Not until I gripped the handle with the bandaged part of my hand and flung open the door.

Clothes and shoes and the rest of my life’s detritus all in a jumble on the closet floor. On the back wall were three giant, jagged lines in marker.

YOU HAVE TWENTY-FOUR HOURS TO LIVE

UNLESS SHE GIVES ME WHAT I WANT

XOXO CULVERTON SMITH

Culverton Smith. The man behind Sherlock Holmes’s poisoned ivory box.

I stared back down at my bleeding knuckle. Behind me, Tom raised his iPhone with one shaking hand, and took a picture.

I RIPPED THE INFECTED SPRING FROM THE DOOR HANDLE. Took my phone from the desk (dead), and its charger. Picked up my suitcase. The whole time Tom was loudly pleading his ignorance—this wasn’t me, I wouldn’t do something like that—like the swine he was until I grabbed him by the shirt with one hand.

“This is what you can do for me,” I snarled at him. “Deal with the cop.”

His eyes were focused on the pinprick of infected blood on his shirt. “But what should I say?”

“Make something up. You’re good at that.”

As I stalked down the hall, I heard Tom’s half-assed babbling. “It’s my fault,” he was saying to the policeman, “it’s my fault, let him go.”

I made it to the front doors before my legs began to give out under me.

Bryony Downs had won. She’d taken “The Adventure of the Dying Detective” and turned it back on us with deadly earnest, not knowing that Charlotte Holmes had used that same story to clear our names. I had no idea what she’d dabbed that spring with, but my brain was supplying a cavalcade of answers. Spinal meningitis, I thought, or malaria. I used to want to be a doctor; I’d wanted to treat the scariest diseases, and now I couldn’t stop running them through my head. Milo was right. She had to be working with the Moriartys; how else could she have access to this sort of thing? She was a puppet, and this was a message directed at the Holmes family.

And the message was going to be my dead body.

I staggered out the front door and down the steps. The next two students were waiting for the officer to fetch them, and one of them stepped forward to help me.

“Don’t touch me,” I said, holding up a hand. “I might be contagious.”

Because that was the worst of it. Nurse Bryony could have made me into some kind of bomb. A patient zero that could take out the whole eastern seaboard. I needed to get inside, away from everyone, and I had to start making a plan. My parents couldn’t know. There was nothing they could do. I wondered if my father would still find all this crime-solving fun after he identified my corpse at the morgue.

No. I wasn’t going to die. I was sixteen years old. I was going to be a writer; I was going to go to college, get a flat in London, or Edinburgh, or Paris. I’d get to know my stepbrothers. Oh, God, I didn’t want my little sister to be an only child. I didn’t want to leave Charlotte Holmes with a controlling family and a brilliant mind and a dead best friend. I didn’t want to imagine her life without me. Maybe it was selfish to think that way, but I couldn’t imagine mine without her.

The sky was open and blue, guileless in its beauty. And the snow everywhere, blinding. The light was beginning to prick at my eyes, and I rubbed at them with the back of my hand. This had to be psychosomatic, I told myself; it had to be in my head. The denial working its hand around me. I can’t possibly be dying, I thought, and tried to believe it.

One foot, then the other. Where was I going? I’d walked, I remembered, up the hill from town. The distance was impossibly far. I’d sit for a minute, catch my breath. If I could just arrange my suitcase—there.

Holmes told me that, when they found me, I’d passed out in a snowbank.

They bundled me into the back of Milo’s town car, her and her brother and his Greystone mercenaries. Blankets. Something hot to drink. Holmes rubbing my chilled hands between hers, strangely smooth and firm. “No,” I’d managed to say, “the blood, it’s contagious,” and then I saw that she was wearing latex gloves.

She knew.

I was racked with chills, and still cold sweat beaded on my forehead before trickling down my face. My mouth burned, my teeth tender to the touch. I couldn’t swallow. My throat didn’t work. Holmes held a bottle of water to my lips and tipped it, gently, into my mouth. I tried to pull off my shirt, thinking, in my delirium, that it was a straightjacket, and she stilled my hands. All the while Milo watched me from behind his glasses, taking copious notes on his phone. On what, I didn’t know. I was a specimen, I thought wildly. I would be experimented on until I died.

When we got to our destination, Peterson had to carry me up the stairs over his shoulder, like he’d rescued me from a burning building. And then there was a bed, with sheets still warm from the dryer, a table beside it. Peterson returned to that table again and again with pill bottles, clean rags. Someone brought in an IV drip and put it into my arm.

What was real? I didn’t know. Milo came in, in a suit and watch chain; he lit a pipe by the window, staring broodingly out over the rooftops. My dog Maggie was there, too, though she’d died when I was six. But she put her shaggy head on my mattress and looked up at me with big wet eyes, telling me in silent words what my sister Shelby was reading that week (A Wrinkle in Time), how much my mother missed me. My hands were made of lead; I couldn’t ruffle her ears the way I wanted. Good dog, I wanted to say. Where have you been?