Alfie lives off the coast of England. Merry lives in New York City. Until Merry and her mother set sail on the Lusitania for England, where Merry's father is recuperating from a war injury. People told them not to go, hearing rumors that the Lusitania might be carrying munitions. But they are desperate to be reunited with Merry's father.

Alfie and his father find a lost girl in an abandoned house on a small island. The girl doesn't speak, except to say what sounds like "Lucy." Alfie's mother nurses her back to health. The others in the village suspect the unthinkable: Lucy is actually German-an enemy-because she's found with a blanket with a German tag.

Told from Alfie and Merry's points of view, this exquisite novel tells of friends, enemies, and unexpected kindnesses.