SOMETIME IN THE NIGHT, the rain turns to snow. At first light, Anna and I push our faces against the bedroom window, watching it come down in quiet flakes. It is thicker here than I ever saw in Nottingham, where city snow quickly turns slushy and brown. The whole world outside is still, except for Thomas trudging through the snow to bring the sheep into the barn, and Bog, who nips at the sheep’s backsides.

“Can I borrow your mittens?” I ask Anna.

“You’re still going there, even though you know you shouldn’t?”

“I have to.”

She squints into the bright world outside. Thomas and Bog are rescuing one of the lambs, which has managed to wedge itself between two fence posts. Thomas’s cheeks are red, and his breath puffs in the air, but then he manages to free the sheep, scooping it up with just his one arm, and tossing it over the fence, where it goes stumbling through the snow to its mama sheep.

“Then I’m coming too,” Anna says.

“You mustn’t! You’re sick.”

“So are you, you naughty goose. I’m tired of this bed, and I’m not a complete invalid, no matter what Dr. Turner says. I want to walk in the snow.” Slowly, frailly, she makes her way over to the cedar chest at the foot of the bed. Just that effort puts her out of breath, though she tries to hide it. Out come woolen mittens and hats and scarves that are all a dull shade of gray. She starts to wind a scarf around my neck.

“The stitches are all uneven,” I mumble as I shrug on my coat and do up the buttons.

“The Americans sent them for the war effort. Poor dears, Americans can’t knit to save their lives, though I suppose it’s good of them to try. Now, put these mittens on and show me how you’re always sneaking around without the Sisters noticing.” She pulls a hat over her own curls, glancing in the mirror to adjust them, then takes her coat off the hook behind her door.

The only other person awake this early, judging by the sound, is Sister Mary Grace, getting breakfast ready in the kitchen. So we tiptoe like stealthy cats down the stairs and along the hallway to the library. There is a door the Sisters keep locked, but the lock on the middle window is broken. I push the window open. We climb out into the scrubby boxwood bushes. We have to leave the window ajar to get back in, but the wool blanket hides the evidence.

The cold air hits us. Anna’s cheeks are already splotchy with red. I worry that this isn’t wise, her leaving her warm bed and the cups of tea brought to her. Her arms and legs are so painfully thin. The covers usually hide them, but now, against the bricks of the hospital, she seems so fragile, a girl made of twigs.

“Go on, then,” she says. “I want to meet this magic horse of yours.” She cranes her neck in the direction of the barn, and her voice rises a little. “Do you think we’ll run into Thomas?”

“Not if we can help it.”

She looks disappointed.

I start sneaking along the row of boxwoods and, once I’m certain the coast is clear, dart across the rear lawn to the garden wall. Anna shuffles behind me. She’s quick and light as a curled leaf, but her breathing is shallow and fast. She leans against the ivy, a mittened hand pressed to her chest. I can hear the rumble starting there. She leans over and coughs into the snow so hard I’m afraid she’ll tear something.

“Anna—”

“I’m fine.”

“I think you should—”

“I’m fine!” She turns abruptly. “What in heavens is that?”

I tip my head up to see what she is looking at. The roof. A foot of snow sits on top like the icing Mama slathers on frosted cakes, only there is a patch where the snow has been disturbed violently. And there are prints. The shape is unmistakable.

“See!” I cry. “Hoofprints!”

Anna doesn’t stop staring at the roof. Her eyes narrow like she’s on the verge of remembering something, but then a gritty sound climbs up her throat, and she doubles over in coughs. They shake her hard, which shakes the ivy, and a dusting of snow powders the air. Her hat goes tumbling off.

Suddenly Bog comes thundering around the corner of the gardens, barking like mad. We’ve been discovered. In another second Thomas trudges round. He stops when he sees us. Bog keeps barking until Thomas gives a sharp sss, and he sits right on cue.

Anna reaches for the ivy, trying to pull herself back up. “Look!” she says in a weak voice. “On the roof.”

Thomas doesn’t glance at the roof as he comes forward to help her stand up. “Yes, I saw those marks this morning, but really, you shouldn’t be out here, Miss Anna. You’ll catch cold. Emmaline, get her hat.”

“Emmaline is going to…show me the sundial garden.”

“Not today she isn’t, not with you looking like that.”

I stand on tiptoe to put Anna’s hat back on her head. I try to angle it the way she likes, so the curls show.

“Maybe another day, Emmaline,” Anna says. “I so badly want to see that horse of yours.”

But the spirit is out of her. Her face is a paler shade than I have ever seen it. Her arms are a thin layer of skin over brittle bone. I think there is more stillwater in her veins now than blood.

Thomas looks back at me. “Are you coming, Emmaline?”

I shake my head.

“Promise you won’t stay out long, then,” he says. When I nod, Thomas helps her back toward the house.

Bog and I watch their two brown coats against the snow. They move slowly, as though each step is an effort. I do not think Anna will talk about walking in snow again.

Thomas whistles, and Bog leaves me too.