A gang of criminals, which includes a piano player and an imposing former convict known as 'Gruesome', has found out about a scientist's secret formula for a gas that temporarily paralyzes anyone who breathes it. When Gruesome accidentally inhales some of the gas and passes out, the police think he is dead and take him to the morgue, where he later revives and escapes. This puzzling incident attracts the interest of Dick Tracy, and when the criminals later use the gas to rob a bank, Tracy realizes that he must devote his entire attention to stopping them.
Running from the law after a bank robbery in Mexico, Dad Longworth finds an opportunity to take the stolen gold and leave his partner Rio to be captured. Years later, Rio escapes from the prison where he has been since, and hunts down Dad for revenge. Dad is now a respectable sheriff in California, and has been living in fear of Rio's return.
At the Texas Centennial in Dallas Autry confuses two girls by being himself and his own stunt double. When cowboy star Tom Ford disappears, Wilson gets his double Gene Autry to impersonate him. But Ford owes gangster Rico $10,000 and Rico arrives to collect. He fails to get the money but learns that Autry is an impersonator and now blackmails Wilson and his movie studio. Original version runs 71 minutes, edited version runs 59 minutes.
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.
When a young South Seas sailor falls overboard, the beautiful daughter of a Polynesian king dives in and saves his life. Thus begins the romance of Johnny and Luana. Though Luana is promised to another man, Johnny whisks her away, and for a brief time the lovers live very happily together. But, when a local volcano threatens their lives, Luana knows that she must sacrifice herself to the volcanic gods in order to save her island.