Mr. Moto in Danger Island is a 1939 American mystery film directed by Herbert I. Leeds and starring Peter Lorre, Jean Hersholt and Amanda Duff. It is part of the Mr. Moto series of films.

Plot

Mr. Moto arrives in Puerto Rico to investigate the murder of an American agent, Graham, and uncovers a murderous smuggling ring. On the ship taking him to San Juan, he unwillingly acquires the services of a dim-witted, but good-hearted professional wrestler Twister McGurk after he teaches him jujutsu. Also travelling with Mr. Moto is Joan Castle, the daughter of the police commissioner Colonel Thomas Castle. Upon landing in San Juan, Mr. Moto is apparently ill with appendicitis. The ambulance that is to take him to the hospital is hijacked by the smugglers led by Captain Dahlen who plan to execute him, but McGurk arrives in time to save him. Mr. Moto was not ill as he claimed, and uses his jujutsu skills to defeat the would-be-assassins. Mr. Moto claimed to need an appendicitis operation in order to find out who is the leader of the smuggling ring. As only a few people around John Bentley, the governor of Puerto Rico, knew that he had reported that he needed an appendicitis operation, he deduces that one of them must the leader of the smuggling ring. Despite being old friends, there is much tension between Bentley and Colonel Castle over the latter's inability to solve the Graham murder case or to discover who the diamond smugglers are.