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...