American, British and Chinese secret agents battle the Japanese Black Dragon Society, a secretive ring that smuggles enemy agents into the U.S. disguised as mummies.

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.

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.