The Hollywood Cowboy Detectives ride again as Hoot Gibson, who has walked away from his western movie career, prepares a wild-west show for the circus. The Hooter invites Republic Pictures flack Sean “Curly” Woods and studio chauffeur Nick Danby for a few days of “rest and relaxation” at a Southern California ranch while he gets his act together.
Unfortunately, they find out the historic ranch house is known locally as Demon House. Built by Confederate Col. Jeb Reynolds following the Civil War, it has a history of death and evil.
Curly, Hoot and Nick are joined by legendary western star William S. Hart and 10-year-old stunt-rider Dick Jones as they battle a ghostly band of Confederate soldiers and a scaly green Banshee that appears out of an electrified, flying white cloud. The cowboys are unsure whether they are dealing with an international, supernatural or extraterrestrial enemy as they encounter the ghostly images, flying saucers and two strange beings with unearthly powers.
G-man Big Jim Webber joins the wild-west performers as the Hollywood Cowboy Detectives ride head-on into the Valley of the Banshee with gun-blazing action, amazing horsemanship and the knowledge that the survival of the civilized world hangs in the balance.