Crime lord Jim Belmont escapes FBI custody and begins a reign of thievery that is thwarted at every turn by Jerry Blake, the FBI's Operator 99.

Girl looking for father who disappeared years before in a jungle, finds herself battling greedy civilized people and savages alike.

Western settlers are being driven off their homesteads and ranches by a combination of Indian raids and attacks by bands of mysterious outlaws. The government sends out famed Indian scout Kit Carson and army officer David Brent to investigate, and Carson discovers that a villain named Pegleg controls an outlaw gang called the Black Raiders, and is using them and the Indians to drive out the settlers so he can establish his own empire. He determines to set a trap to expose the identity of Pegleg while avoiding traps and ambushes that Pegleg is setting for him.

Three government aviators called the "Flying G-Men", one of whom is disguised as "The Black Falcon", fight to protect the US and its allies from an enemy spy ring and to avenge the death of the fourth Flying G-Man.

A famous detective sets out to discover who stole $2 million in bonds.

A young radio cop and a beautiful girl try to stop an international criminal gang from getting their hands on the formula for a new bulletproof steel.

A scientist invents a poison gas; the villain and his gang will do anything to get the formula; our hero, "Lightning Hutch", is sent to save the scientist, the scientist's beautiful daughter, and the formula.