Scotland Yard Inspector

As Danny McMara and his girl friend drive through a thick London fog, she asks him to stop and get out, then runs him over. Nearby, Danny's sister Heather awaits him in a bar, while Philip Odell, an American magazine writer, waits for the fog to lift enough for his plane to take off. After a policeman arrives and calls in a report of a dead man, Phil accompanies Heather to see the accident. She believes her brother was murdered, and Phil, who is attracted to Heather, takes her to see his pal, Scotland Yard Inspector McGlendon. He rushes into the chief inspector's office, and after pounding his friend on the back, is chagrined to discover that "Mac" has been replaced by dour Inspector Rigby. Rigby, unimpressed by Heather's lack of evidence, warns Phil not to do any amateur sleuthing, but Phil ignores him. He begins his investigation at Danny's favorite nightclub, Peggy's, where he meets the beautiful eponymous proprietor, who cannot help them. Bribing the waiter, however, produces the address of Danny's hotel. Pretending to be Danny's friend, Phil gets the key to the room, but once inside is knocked out by a stranger hiding behind a curtain. He revives and finds an audio tape just as Rigby bursts in. Phil is discovered by the annoyed inspector, who, though suspicious, releases him. On the way out, Phil steals Danny's mail and uncovers a letter from actress Marilyn Durant. He visits her, but finds her passed out from an attempted overdose. Phil calls Heather over, and together they revive Marilyn, who informs them that she loved Danny and was devastated when he informed her that he was engaged. She supplies them with the name of Danny's old boss, movie producer Christopher Hampden. After Hampden claims to know nothing about Danny's death, Phil tells Heather that he cannot solve the crime, and when she asks him why he bothered trying, he kisses her in response. He resumes his plans to leave England, but upon discovering that his hotel room has been ransacked, he insists that Boswell, the airport manager, who has gotten permission to fly around the fog through Communist-controlled airspace and back to America, cancel his reservation. He next runs the tape in a record store and hears a man confessing, at the urging of a woman named Margaret, to setting a fire in a garage which killed his partner, George Maybrick. Phil tries to replay the tape for Heather, but accidentally erases it. Hours later, he finally remembers the name of the garage, and there he learns from the fire chief that Hampden and Martin Sorrowby were Maybrick's partners, and that Danny had questioned him about the same fire. Now convinced that Danny was murdered for blackmailing Hampden, Phil races to the producer, who denies Phil's suspicion then has him followed by his flunky, Connors. Phil tracks Sorrowby to a mental institution and finds his room, even though Hampden's friend, Dr. Campbell, insists that Sorrowby is dead. Sorrowby confesses that Maybrick developed a world-class carburetor but then insisted on giving the patent to the government. When his wife Margaret discovered this, she pushed Sorrowby and Campbell to kill him. Sorrowby then informs Phil that he cannot distinguish between fact and fiction. Dr. Campbell bursts in, and although Phil escapes, she has Sorrowby killed for talking to him. After Connors tells Hampden about Phil's involvement, Hampden informs Margaret he will have Phil killed. Meanwhile, Phil convinces Rigby to accompany him back to the institution, but once they learn that Sorrowby is dead, Rigby orders Phil to stop investigating. Instead, Phil visits the garage ruins, where he finds a photograph of Margaret and recognizes her as Peggy. Just then, Connors knocks him out and informs Hampden about the picture. Margaret then coerces Heather to accompany her to Hampden's, and drives her there in a thick fog. Although Margaret tries to run Heather over, her plan is foiled by a policeman, so she brings Heather to Hampden's office to finish the job. Phil, who has learned that Heather left with Margaret, races to Hampden's in time to rescue her. Heather and Phil run to the basement, followed by Connors, Hampden and Margaret, who shoot at them. As Connors fights Phil, Hampden mistakenly shoots his flunky and then falls from some scaffolding. Instead of helping, Margaret races out of the building. Phil tries to save Hampden but he falls to his death, while Margaret jumps into a car and quickly crashes it trying to drive through the fog. Days later, Rigby thanks Phil, who brings Heather with him to fly to America. When Boswell recognizes him, however, he refuses them a reservation, and Phil hopes aloud that Heather does not get seasick.