Trigger, billed as "The Smartest Horse in the Movies," is a kidnap victim in Under California Stars, the film that celebrates Roy Rogers' 10th anniversary as a film star.
There's a shady gang traveling the range, making a living rounding up wild horses and selling them for their meat and hides. When the gang tries to raid Roy's land, Roy manages to thwart their plans and make enemies of them. The gang soon retaliates and steals Trigger, offering him back to Roy for a $100,000 ransom. To make matters worse, Roy suspects that his friend Ted Conover (Michael Chapin) may have helped with the kidnapping.
The film features exciting chases and many musical numbers in which Roy and the Sons of the Pioneers shine.