Charlie's visit to Paris, ostensibly a vacation, is really a mission to investigate a bond-forgery racket. But his agent, apache dancer Nardi is killed before she can tell him much. The case, complicated by a false murder accusation for banker's daughter Yvette, climaxes with a strange journey through the Paris sewers.

When a friend of Charlie's is found kicked to death by his own race horse on board a Honolulu-bound liner, the detective discovers foul play and uncovers an international gambling ring.

A district attorney and a reporter try to find the killer of a D.A. who uncovered a massive stock fraud.

A scientist working on cures for rare afflictions, such as a bone softening agent made from molds to allow him to correct the spinal deformity of his nurse, finds the physical causes of lycanthropy in wolf-man Larry Talbot and of vampirism in Count Dracula, but himself becomes afflicted with homicidal madness while exchanging blood with Dracula.

When the villagers of Klineschloss start dying of blood loss, the town fathers suspect a resurgence of vampirism. While police inspector Karl remains skeptical, scientist Dr. von Niemann cares for the vampire's victims one by one, and suspicion falls on simple-minded Herman Gleib because of his fondness for bats. A blood-thirsty mob hounds Gleib to his death, but the vampire attacks don't stop.

Two lonely people in the big city meet and enjoy the thrills of an amusement park, only to lose each other in the crowd after spending a great day together. Will they ever see each other again?