She was shivering. I’d never seen her this way, so fluent at this grasping. Her face twitched as though she were trying to hold her features steady while something happened underneath. She took my hand. Her fingers were greasy with lotion. “I need Matilda,” she said. Her voice was calm and sure, as if this request was entirely reasonable. I’d never heard of anyone named Matilda.

I gripped her wrist and slid one hand under the hunch of her back. Her skin was loose between the bony marbles of her spine. “Don’t pull,” she said. “It hurts.”

I called my brother. Tom said, “You need to ask her: ‘Lucy, did you hit your head?’” I cupped my palm over the phone and waited for her reply. He waited for me.

“It was only yogurt,” she said. “Just a little bit I wanted.”

I knelt down next to her. My boots squeaked on the linoleum. “But did you hit your head? Can you tell me that?”

“If I had,” she said. “I’m not sure I would remember.”

I reported back to Tom. He said I should keep her awake for at least two hours. This was the rule he remembered about concussions, in case she had one. He was with our mother, Dora, on the other side of the country, probably sipping seltzer at a Pacific restaurant where everyone was thinking cheerfully unconcussed thoughts about their sushi. It was a first-generation place, he told me, mercifully open on holidays. It was the first day my mother had taken off work in months.

“Tom?” I asked. “Do you know anyone named Matilda?”

“One sec,” he said. “I’m putting Mom on the phone.”

Her voice was loud and sudden: “You need to do what Stella says! You need to let her take care of you!”

“Are you trying to talk to Grandma?” I asked. “Should I give her the phone?”

“Oh,” she said. “Of course.”

Grandma Lucy gripped the cell phone with her quaking fingers. My mother spoke so loudly that her voice sounded like it was coming from the floor under Grandma Lucy’s ear. She rolled onto her side and handed me the phone. Tom said, “Two hours, yeah?” I heard noise in the background, the rustling of glass and gossip. I hung up.

Grandma Lucy didn’t want any gingerbread or tea. She didn’t want presents. She just wanted to go to sleep. It wasn’t dark yet, not even close. The day had been ruined, she insisted. She wanted to wake up and have Christmas tomorrow.

I checked my watch. I took a breath. Two hours: I would do this. We found a holiday special on television. Animated clay reindeer scampered across the glittering snow. I had to keep shaking Grandma Lucy to make sure she was awake. “Hey,” I said. “You’re missing the part with the reindeer. With the snow.”