Sam Coyle’s father lived in the shadows–an undercover agent among the spies and radicals of Cold War London. That world claimed his life, and Sam is haunted by his absence. He left nothing behind but his enemies; nothing to his daughter but his tradecraft and paranoia. Now, her boyfriend Luke is missing too–the one person she could trust, vanished into the fog on the Kentish coast. To find him, Sam must follow uncertain leads into a labyrinth of blind channels and shifting ground. She must navigate the treacherous expanse of the salt marsh.