Her name was Agnes Hale, and in the winter of 1917 she worked nights at a field hospital outside Ypres. Most of the nurses hated the night shift. Agnes asked for it. She'd pull a stool up to whichever bed was worst off, hold the man's hand, and talk to him about nothing: the weather back home, what his mother cooked on Sundays. A lot of those boys died looking at her.

Somewhere along the way she decided that was the problem. She got it into her head that they couldn't let go while her face was the last thing they saw, that she was keeping them here. So she started covering it. First with gauze, then with a cloth she never took off. One morning the orderlies found her with a surgical needle, sewing her cap to her scalp. The doctors wrote "shell shock" in her file and moved her to the supply tents, away from the patients.

She was back on the ward the night the shell hit, 11 March 1918. Nobody knows who let her in. The canvas went up in seconds. The men who got out said she kept going back in for the ones who couldn't walk, and she was still inside when the roof came down. They never found her.

The soldiers who lived through that front kept telling the same story, long after the war. If you're dying and there's no one with you, you'll smell smoke first, and carbolic soap. Then there's a nurse at the foot of your bed, tall and thin, her uniform burned black. Her tools rattle at her belt, and there's a glow through the cracks in her hands, like coals.

She doesn't have a face anymore. People say that's so you won't be scared.

She's never hurt anyone. She just sits with you until it's over, the way she always did. There's a new stain on her apron every time.