Grey came that very night like Romeo and threw little stones at my window until I opened it. It was past midnight. She beckoned me into the dark. I put a coat over my pajamas and climbed down the tree that grew close to the house. It was the first and only time I have snuck out. We went to a pub in Golders Green and ate salt-and-vinegar chips in a haze of other people’s smoke. It was like meeting in secret with a lover, except I was thirteen and my clandestine liaison was with my estranged older sister.

In the six months since I’d seen her, Grey had cut her white hair into a long bob that skimmed her shoulders. She wore a black turtleneck and cat eyeliner. She looked like an assassin from a spy movie. We talked about what she’d been doing, where she’d been living, the boys she’d been dating. She showed me pictures of herself on her phone, beautiful images that would soon run in magazines and appear on billboards. She was on the precipice of intense and immediate international fame, though neither of us knew it yet.

“Come and live with me,” she said at one point. “You don’t have to stay there anymore. You don’t owe her anything.”

It was a tempting offer. I wanted to go—and I wanted to stay. I was split between the two halves of my heart. “She’s my mother,” I said finally. Grey frowned like she wanted to dispute that but couldn’t. “I can’t leave her all alone. I’m all she has left.”

So I stayed, on the condition that I could see and talk to Grey whenever I wanted. Cate allowed it, begrudgingly.

The first and only time Grey reentered our house since leaving was to pack up her bedroom. We spent the next afternoon dumping all her bric-a-brac into boxes bound for storage until she had enough money for her own apartment. I wanted to linger over each piece of treasure, to slip lipsticks and candle stubs into my pockets to marvel at later, but she watched me with eagle eyes, and it all went where I had chosen not to follow.

“If Justine or her little Barbie sidekick give you any more trouble, let me know,” Grey said as she carried the last box out the front door. “I’ll take care of them.”

Before she left, Grey went upstairs to speak to Cate. I followed behind her quietly and listened at the door, hoping to hear them reconcile, but that was not what I heard. “If you hurt her,” Grey said to our mother softly, “if you so much as harm a single hair on her head, I will come back here and I will kill you.”

If Cate answered, I didn’t hear it. I went to the bathroom and vomited. I thought of Justine Khan and how I could never unleash my sister on her, no matter how mean she became, because Justine was just a girl and my sister was something more, something crueler, the thing in the dark. Grey left without saying goodbye. Somehow, whatever she had said to my mother the night she threw her out was even worse than the death threat.

Here is a terrible truth I had known for as long as I could remember: I was my mother’s favorite child. I was orderly and docile and quiet, and those traits made it easy for her to like me, to understand me. My sisters were difficult girls: too sexy, too angry, too hard to handle. They wanted too much. They were too willing to put their bodies and lives in the way of the world. In the months and years after Grey and Vivi evaporated from our day-to-day, life was better. I learned to live without my sisters as my constant companions. I became myself. The strangeness that haunted them decreased to a low simmer when they weren’t around.

Cate and I fell into an easy routine. We watched Doctor Who and drank herbal tea curled up on the couch. We donned Wellingtons and took long strolls in London’s marshes, foraging for knotweed to make jam and elderflower and nettle to make summer cordial. We took flowers to my father’s grave every other week. Without my sisters there to cause trouble, I settled into what was left of my little family with ease.

* * *

Tyler rolled his eyes. “Ugh, your mother does not hate Grey, Iris. So dramatic.”

I stared at the door through which she had left. “No, she does.” I knew it profoundly. I had known it since the night Grey left home. I knew it on the nights I curled up next to Cate on the couch. I knew it in the mornings when we ate our homemade jam. As surely as many children know they are loved, I knew that Cate despised my sister. “She manages to mask it most of the time, but there’s something . . . ugly underneath. I see it sometimes. Cate is afraid of her. I don’t know why.”

“You sound like you belong in the psych ward with your sister.”

“And I thought you were going home.”

“Yes, well. I look like utter garbage. I can’t let the paparazzi shoot me in this state.” A lie to mask the truth: He was worried about Grey too. “I always knew Grey was a bit . . . off. I liked it. It seemed, I don’t know, dangerous in a sexy way. I never thought she was completely nuts, though.”

“I don’t think she is.”

“Oh, please. You heard what the doctor said.”

“I’ve also seen things over the past week that I can’t explain. If it’s all in Grey’s head, why can Vivi and I see it too?”

“Folie à deux, Little Hollow. Or in this case, folie à trois.” Tyler tapped my temple. “Sometimes madness is catching.”

Vivi came back an hour later, once darkness had settled over the city, the knuckles of her right hand raw and bleeding from punching a photographer as he tried to manhandle her for a picture. The three of us went down to the hospital cafeteria together and ate prepackaged sandwiches and old oranges for dinner, then trudged back upstairs to wait and wait and wait. Vivi went to sleep again, her hand bandaged and iced by a nurse. Tyler stared dead-eyed at his phone screen, scrolling through tweets and Instagram posts about Grey’s disappearance and subsequent miraculous return. The story was blowing up on social media. There was already a fan-art meme trending online of Grey as a venerated saint rendered in watercolor, a banner behind her reading “In Hollow we trust.” Dozens of celebrities had reposted it, rejoicing at our sister’s return. I watched over Tyler’s shoulder for a while, and then, even with the plastic chair beneath me biting into my bones, I eventually slipped into a fraught and fitful sleep.