Johnny Mack Brown was recruited by Chet Norman, the owner of a stagecoach line, to end the heist perpetrated by a mysterious knight who plays strange notes with a hiss…

Two federal agents battle a gang that hijacks trucks carrying materials vital for the security of the country and sells them to foreign powers.

Jungle Jim must protect rare pony-like animals whose glands produce a powerful narcotic. On the way, he fights a giant spider.

A mysterious masked rider and his gang are murdering ranchers and robbing stages. Government Agent Johnny Mack Brown has been called in to help the Sheriff.

A marine biologist and a government agent investigate mysterious deaths and rumors of a sea monster in a secluded ocean cove, and find themselves involved with a marine biology professor…