Brother and sister, Nathaniel and Rachel, are left behind in London at the end of World War II. Their father leaves first, moving to Singapore, with their mother following shortly after. The reasons for their leaving are not quite clear, and get even more mysterious when the teenage siblings find the trunk that their mother so meticulous packed for the trip abandoned in the basement.

Left in charge of their care at this time is a boarder called “The Moth.” Nat and Rachel do not know much about him, suspect that he may be a criminal or spy, but soon grow attached to him and no longer care as much about his background. The Moth introduces a rotating cast of colorful and intriguing characters into their lives, with Nat noting, “the house felt more like a night zoo, with moles and jackdaws and shambling beasts who happened to be chess players, a gardener, a possible greyhound thief, a slow-moving opera singer.”

Just as mysteriously as she left, their mother comes back months later without their father, and without any information on his whereabouts. An older Nathaniel looks back on this time and tries to make sense of it and find answers to the many questions that linger, in particular his mother’s involvement in the war and where her many scars, both physical and emotional came from.