The writing was bubbly and cute, the i’s dotted with pink hearts. Grey had written this when she was a kid, maybe only twelve or thirteen, before she’d switched to the acid-green pens and thin script she’d favored in high school. WHAT DID I DO? was the last annotation. It was in the margin of a Wiki printout about the disappearance of Mary Byrne, a British teenager who’d gone missing from Bromley-by-Bow on New Year’s Eve in 1955. Folded into the pages were a handful of Polaroid pictures Grey had taken when we went to Bromley-by-Bow to stay with my mother’s cousin the week after our father died. We’d stayed near the station, across the river from where Mary Byrne had last been seen decades ago.

What I remembered from that week: The four of us slept on an air mattress, our bodies stuck together in the heat, a fen of salt and sweat and grief; I fell over in the long summer grass of Mile End Park and skinned my knees on hidden rocks; I wore pink shorts and applied chocolate-flavored lip gloss at an alarming rate; my mother cried every night; I stroked her hair until she fell asleep; Grey slept rigid against the wall, her back to the rest of us; I missed my father.

Grey had been obsessed with Mary Byrne, another inexplicableNew Year’s Eve disappearance, and had spent much of her time in Bromley-by-Bow wandering the streets from dawn to dusk. Vivi and I had been too young to go with her, and Cate and the other adults were too distracted with funeral planning to notice or care much what Grey did. It was a rare opportunity, this relaxing of Cate’s constant surveillance, and thirteen-year-old Grey took full advantage of this taste of freedom, slipping into the streets of East London by herself every day and returning every night, frustrated.

Then, on our last night there, the night before our father’s funeral, Grey had come back giddy with excitement and grinning from ear to ear. It was the happiest I’d seen her in a long time. She smelled of something wild and green.

The photos in the journal were all dated from that day, the day before we buried our father. The first four were of areas around Bromley-by-Bow: the Greenway, a footpath and bike freeway that stretched for miles through London, bordered in Grey’s picture by tall white apartment blocks set against a darkening sky; the boxed-in metal footbridge that stretched over West Ham Station, the last place Mary Byrne had been seen; an exterior and interior shot of the House Mill, a huge old tidal mill on Three Mills Island that had burned down and been rebuilt in the nineteenth century.

The final picture showed a ruined doorway: a freestanding stone wall with an archway at its center. It was inside, perhaps in the basement of the mill, persevered by the new buildings that had been constructed above it. White flowers grew rabid across its surface. It looked much the same as the doorway that had been embroidered on Grey’s quilt.

A chill settled across my skin.

“Did she think she’d figured out the Mary Byrne mystery or something?” I said.

The rest of the journal was filled with nothing but sketches of ruined doors, their location and a date recorded beneath them. Doors in Paris, doors in Berlin, doors in Krakow. Doors in Anuradhapura, doors in Angkor Wat, doors in Israel. Had Grey been to all of these places?

The barista leaned over the counter then. “You guys . . . uh . . . you guys okay?” she asked.

“We’re fine, thank you,” I said. “Sorry, we’ll order something in a second.”

“No, I meant . . . um . . . you’re bleeding on the floor just a tad.”

“Oh. Yeah. We, uh . . . fell off our bikes. Do you have a first aid kit?”

The barista brought us the supplies and a free cappuccino each to boot. Vivi and I sat together at the back of the now-empty café, drinking coffee, the green-and-white box splayed open on the table between us.

Vivi sat with her hands resting on her knees, palms up, as I swabbed her cuts with iodine.

“Grey’s dead, isn’t she?” she said flatly. Her eyes were deep wells. She didn’t even wince at what must have been stinging pain. “There’s a crucial time frame of forty-eight hours, and after that, they’re dead.”

“Don’t say that,” I warned. “That isn’t what happened to us.”

“What do you remember about being gone?” Vivi asked.

“I don’t remember anything.”

“I know that’s what we tell each other. I know that’s what we tell the world. But I remember white petals drifting through the air like autumn leaves. And smoke. And dusk. And . . .”

A fireplace. A girl with a knife in her hand.

“Don’t,” I said. “You were nine. I was seven. We can’t trust those memories. Let me see your arm.”

“There was a girl.”

“Stop it.”

“I think she did something to us. I think she hurt us.”

“Vivi.”

“You asked, ‘Who cuts little girls’ throats?’ Don’t you want to know what happened to you?”

“No.”

“Why not?”

“Because . . . I’m afraid.”

“You shouldn’t be afraid of the truth. It’ll set you free, right?”

“Unless it’s so terrible it screws you up entirely. No, thank you. Maybe I’m totally fine with my repressed memories. Now show me your arm.”

Vivi shrugged out of her jacket and rolled up her bloody sweater, her skin prickled with goose bumps. I unwrapped the scarf we’d used to stanch the bleeding. The fabric was sodden with gelatinous blood and smelled heady and wrong.

I faltered when I saw the wound. “Hold still,” I ordered as I swabbed it with an alcohol wipe to get a better look. “There’s something here.”

Vivi wasn’t paying attention. “We are going to get her back, Iris,” she said as she stared at the ceiling, still unconcerned by the pain. “I will not live in a world without her.”