James Houghland, inventor of a new method by which television signals can be instantaneously sent anywhere in the world, refuses to sell the process to television companies, who then send agents to acquire the invention any way they can. On the night of his initial broadcast Houghland is mysteriously murdered in the middle of his demonstration and it falls to Police Chief Nelson to determine who the murderer is from the many suspects present.
After a series of murders, a man finds out that his mother was bitten by a vampire bat during her pregnancy, and he believes that he may be the vampire committing the murders.
Holmes, retired to Sussex, is drawn into a last case when his arch enemy Moriarty arranges with an American gang to kill one John Douglas, a country gentleman with a mysterious past. Holmes' methods baffle Watson and Lestrade, but his results astonish them. In a long flashback, the victim's wife tells the story of the sinister Vermissa Valley.
While vacationing in St. Moritz, a British couple receive a clue to an imminent assassination attempt, only to learn that their daughter has been kidnapped to keep them quiet.
On the French coast, unlucky Marie Galante is abducted and forced to board an American cargo ship bound for the Panama Canal. When an escape attempt leaves Marie high and dry in the Yucatan, she takes work as a nightclub singer to earn her safe passage to the Canal region. But Marie faces bigger problems when she gets mixed up in a destructive plot against the U.S. Naval fleet, and so she accepts the kindly assistance of secret agent Dr. Crawbett.
The owner of a large mansion in the country throws a costume party for some of his friends. However, the party turns sour when he is found stabbed to death in a closet. The police and a guest try to discover who committed the murder.
A singer on a gambling ship is married to a wealthy playboy. When he is found murdered, all evidence points to her as the culprit, and she is put on trial for the crime.
Rival newspaper reporters Pat Morgan and Ted Rand find themselves unraveling the mystery behind the death of a millionaire philanthropist who fell from his penthouse balcony. When it is discovered that the plunge was not an accident, the building's residents come under suspicion. Soon, the body count begins to mount as three more murders occur by strangulation.
When legendary hunter Bob Rainsford is shipwrecked on the perilous reefs surrounding a mysterious island, he finds himself the guest of the reclusive and eccentric Count Zaroff. While he is very gracious at first, Zaroff eventually forces Rainsford and two other shipwreck survivors, brother and sister Eve and Martin Towbridge, to participate in a sadistic game of cat and mouse in which they are the prey and he is the hunter.
Francis, a young man, recalls in his memory the horrible experiences he and his fiancée Jane recently went through. Francis and his friend Alan visit The Cabinet of Dr. Caligari, an exhibit where the mysterious doctor shows the somnambulist Cesare, and awakens him for some moments from his death-like sleep.