When the king of a small country is assassinated, his diplomats hire Sherlock Holmes to transport and guard his son and heir on a steamship from England to Algiers. But sinister agents are aboard - can any of the ship's crew and passengers be trusted ?<br /><br />This is probably the weakest of the forties Sherlock Holmes classics, and isn't really a mystery story at all - Holmes is nothing but a glorified bodyguard in it, it has a contemporary setting (for the time) and even by this series of films' standards it looks threadbare and hurried. It's not really all that bad though and it does have several quirky and interesting ideas; the suspicious pair discussing dead bodies who turn out to be archaeologists, the deaf-mute killer who talks in sign-language, a bomb in a party-cracker, Holmes' ingenious dupe for hiding the king, and so on. A minor film, given the talents of Rathbone and Neill, and a million miles removed from Arthur Conan Doyle's iconic hero, but still a pleasant enough way to kill an hour.