Ken Williams is determined to discover the identity of the mysterious Rattler, who preys upon railroads and transportation companies like that owned by Jane Corwin. The Rattler is especially difficult to catch because of his skill at disguising himself as other people.
Rex, a wild stallion, and Rinty, a police dog, are pals. Their master , John Sheldon, is framed for murder, and Alice Ingram plans to race Rex for money to pay for John's legal defense. Meantime, Frank Nolan, who has falsely accused John, sets out to steal Rex for himself.
Gangster Chandler and his accomplice Tracy arrive at a dude ranch. Cowboy Kentucky arrives at the same time. When Tracy double-crosses his boss and has the stage robbed, Kentucky finds the outlaws and brings them in. Tracy frames him for the murder of the driver but his pal Cactus gets him out of jail. He returns just as Chandler shoots Tracy and Kentucky finds himself arrested for another murder.
When the ancient continent of Mu sank beneath the ocean, some of its inhabitant survived in caverns beneath the sea. Cowboy singer Gene Autry stumbles upon the civilization, now buried beneath his own Radio Ranch. The Muranians have developed technology and weaponry such as television and ray guns. Their rich supply of radium draws unscrupulous speculators from the surface. The peaceful civilization of the Muranians is corrupted by the greed from above, and it becomes Autry's task to prevent all-out war, ideally without disrupting his regular radio show.
Expelled from his lieutenancy in the Marine Corps, Bill Traylor reenlists as a private. His unit is sent to a Latin American country where a rebel leader called The Torch promotes insurrection. There Traylor encounters again Captain Benton, the man responsible for his disgrace and his rival for the love of a girl.
Hank Davis, foreman on a huge dam project, enlists the aid of his two flyer friends when a sinister figure known as The Black Ace leads his Mystery Squadron of masked pilots in an attempt to destroy the dam.
Corporal Larry Grant and Sergeant "Mac" McGowan, of the United States Marine Corps, are rival for the love of Frances Schiller, but team up to hunt down "The Tiger Shark," a mad, scientific wizard who is holding Sergeant William Schiller, Frances' brother, a prisoner on a wild, jungle island in the Pacific.
Easter, a soldier of fortune and gunrunner, leaves his family behind escaping from the authorities and an American detective named Mason. His globe hopping escape leads him finally to South America, where he is hired to organize a band of revolutionaries, unaware that they plan to eliminate him when his job is done. Here, also, he encounters his own son, on track to waste his own life in pursuits similar to Easter's.
A gambling ring run out of the Mogul Taxi company is intent on fixing college football games. Football star Harold "Red" Grange is a target for the gamblers, whose thugs try to eliminate Grange from playing. Grange's buddy Buddy is himself vulnerable to blackmail, since he has broken team rules by marrying. The crooks use all their wiles to keep Grange and Buddy from leading their team to victory.
Bob Preston, publicity man for Superba Pictures, uses his publicity skills in an attempt to make this fiancée June Dale the most famous movie star in the world. But in doing so, he forgets that women want to be attended to for themselves, not as objects of fame.
Clyde Beatty, an animal trainer and circus star, leads a search for his missing girlfriend and her father who were on an expedition looking for a lost tropical island. Using a dirigible as his mode of transportation, Beatty and his band head off in search of the missing explorers only to crash their airship on the same island their friends are located. Battling wild animals and a gang of greedy men searching for gold, Beatty and his party must rescue his girlfriend and father all the while trying to escape their jungle island. Feature version of the same-title serial of the same year, with refilmed sequences substantially altering the plot and characters of the original chapterplay.
When the daughter of a newspaper publisher is falsely charged with murder, a reporter on her father's paper goes into hiding with her. At first hoping to get an exclusive story, the reporter eventually finds himself falling in love and trying to find the real killer.
The Wrecker wrecks trains on the L & R Railroad. One of his victims is Larry Baker's father. Baker wants to find the evildoer, among a host of suspects, but it will be difficult since the Wrecker can disguise himself to look like almost anyone
Both the Range Buster and Rance and his outlaw gang are looking for stolen gold bullion. To scare people away from the ranch where the gold is hidden, Rance has his man imitating ghosts. The gold is in a steel cased organ but a certain combination of organ stops need to be pulled to obtain the gold.
Natty Bumppo, known as Hawk-Eye, is a frontiersman in the American wilderness. Together with his Indian friends Chingachgook and Uncas, he fights battles against nefarious white soldiers as well as the vicious Indian Magua and his cohorts.
Jane Eyre is an orphan who was raised by her aunt until she came to Thornfield Hall as governess to the young ward of Edward Rochester. But Jane is attracted by the intelligent and energetic Sir Rochester, a man of almost twice her age. But just when Sir Rochester seems to pay attention to her, he invites the beautiful and wealthy Blanche Ingram to stay at his house.
The story of a boy, a dog, and a man. The boy discovers he is heir to a shipping line, and travels to Los Angeles, accompanied by inventor/radio operator Bob Whitlock and Irene Blaine. Their journey is aided by Pal, a wolf dog.
A prospector is murdered by The Cactus Kid and his gang, who hope to find the murdered man's goldmine. The miner's dog, Rin-Tin-Tin, recognizes the killers, who thereafter seek to use the dog to locate the lost mine. With the help of a government agent and a young girl, Rinty saves the mine and brings the bad guys to justice.
A mysterious master criminal known as The Voice plots with his gang to sabotage the Milesburg Oil Company, but the rightful heir has a secret army of her own to protect her rights.
After suffering a traumatic injury, a policeman resigns from the force and, after he's saved from a suicide attempt, goes to work at a café frequented by gangsters.
