Rancher Roy and his boys track down a gang who have stolen Trigger and are holding him for ransom.
Roy has just finished his latest film and leaves for his ranch where he will be broadcasting a show celebrating his tenth year in movies. When Roy and Trigger arrive at his ranch he finds Cookie has hired his relatives. Caroline, the only relative that doesn't have a strong resemblance to Cookie, is the horse trainer. Bob Tells Roy a gang of men are hunting range horses. Roy puts a stop to hunting on his land. Pop decides there's money in kidnapping Trigger and demands a $100,000 ransom. McFarland's stepson, Ted, and his dog Tramp, run away and is found hiding in Roy's barn. A trap is set to catch the kidnappers ranch.
UNDER CALIFORNIA STARS (1948) is a fairly typical postwar Roy Rogers vehicle with a routine B-western plot enlivened by some excellent Trucolor photography. Roy plays himself, the movie star dubbed `King of the Cowboys,' and is briefly glimpsed on the Republic Pictures soundstage before the action quickly shifts to Roy's rural property, the Double R Ranch, for the occasion of a radio broadcast celebrating the star's tenth anniversary in movies. The event is marred by the kidnapping of Roy's palomino, Trigger, by a group of henchmen working for Pop Jordan, a local horse trader. Ted, a boy who ran away to Roy's ranch after mistreatment by his stepfather, witnesses the kidnapping but is warned to keep quiet or they'll kill Ted, Trigger AND Roy.
Given the fame of Roy and his horse, it seems a mite foolhardy to go around kidnapping Trigger, especially since the event makes national headlines. But, in the insular alternate universe of the postwar B-western, the matter is left entirely up to the local sheriff of Saddleback, a town which offers no sign of a gas station, diner or paved road. Neither the FBI nor the state police nor any other pertinent law enforcement agency is called, nor do they show up on their own. (Had J. Edgar Hoover never heard of Trigger? Was he too busy chasing commies? Or did he simply not exist in this world?)
Eventually, Roy and his crew, which includes Cookie Bullfincher (Andy Devine) and Roy's backup singers, Bob Nolan and the Sons of the Pioneers, work with the sheriff to come up with a plan to trap the kidnappers when they show up for the ransom money. There is lots of outdoors action and furious horse-riding, before a violent confrontation or two ends the problem. The action is shot almost entirely on location, with none of the studio-shot closeups that one finds in a later Roy western like NORTH OF THE GREAT DIVIDE (1950).
There's a surprising amount of bad behavior and violent death on display. Even though these films were set in the modern era, they featured typical B-western type villains who were invariably local businessmen who are secretly corrupt and embark on capers which threaten Roy in one way or another. A somewhat alarming development in this film is the constant threatening of Ted, the runaway boy, first by his stepfather, Lige, Pop Jordan's chief assistant, and later by another henchman, Ed, who threatens to blow Ted's head off if he says a word about who kidnapped Trigger. These darker elements serve to counterbalance the song and comic interludes. The lead villains here are authentically crusty, hefty western types, well-played by George Lloyd and Wade Crosby.
Andy Devine provides the comedy relief, a role that would be taken by Gordon Jones and Pat Brady in future Rogers westerns. Singer-actress Jane Frazee is the female lead, playing a cousin of Cookie who comes to the ranch to train horses. The catchy title song is heard more than once, culminating in a lovely duet performed by Roy and Jane. The film is not as well-plotted or packed with incident as such later Rogers Trucolor westerns as THE GOLDEN STALLION and TRIGGER JR., but it remains a must for Roy's fans.