Just after World War II, Nathaniel and his older sister Rachel stay behind in London when their parents move to Singapore, leaving them in the care of a mysterious figure named The Moth and his eccentric crew of friends. These friends are men and women joined by a shared history of unspecified service during the war, all of whom seem, in some way, determined now to protect and educate Rachel and Nathaniel. Their mother returns after months of silence-- without their father, explaining nothing. A dozen years later, Nathaniel begins to uncover all that he didn't know and understand in that time.