A remote Baltic island reveals human remains tied to shipwrecks, piracy, and a hidden maritime past. The unexplained disappearance of three lighthouse keepers on a Scottish island sparks one of the world's greatest unsolved mysteries. A tropical Pacific island conceals a vast underwater graveyard of military equipment dumped in a moment of wartime defiance. And a fortress prison off the coast of France holds the secret of a masked prisoner whose identity remains one of history's most enduring enigmas.