On the way to a performance, Cal Shrum and his musical group, the Rhythm Rangers, are fired at by a masked bandit. Soon after, they encounter Cal's brother Walt and his group, the Colorado Hillbillies. The two brothers decide to team up, but Walt changes his mind when he learns that Cal is heading for Big Bend. Despite Walt's warning that entertainers are being shot in Big Bend, Cal and the Rhythm Rangers resolve to continue to the town. When Frank Lawson, the hotel's owner, refuses to rent them rooms, they proceed to the theater, where manager James Beeton warns them that no one will come to their show because they are worried about the danger. After the sole member of the audience leaves the theater, Cal orders Max "Alibi" Terhune, one of the performers, to open the theater doors so that the townspeople can hear them. Shortly afterward, they are shot at by a masked gunman. After learning that the gunman earlier murdered a magician who was performing in town, Cal vows to catch the killer. Using a recording and Elmer, Alibi's dummy, Cal sets a trap for the gunman, who later eludes him during a chase. Alibi discovers that some townspeople believe that Beeton is the killer, because his daughter Mary ran away with Tom, a man in a magic show. He has not been jailed, however, because the sheriff is out of town. After a group of men led by Beeton demand that Cal leave town, he agrees to go at daybreak. In the morning, the Fargo agent offers to let Cal and the Rhythm Rangers stay with him, if they will play a few songs. They then continue their investigation and determine from the bullets that the gunman was using an old Sharp's rifle. Together with Don Weston, Cal follows the gunman's trail. During their investigation, they encounter the sheriff and explain their dilemma. Meanwhile, Mary returns to town, having changed her mind about marrying Tom. As she rides into town alone, the masked man kidnaps her. Cal and Don find her abandoned horse and follow the masked man's tracks to a shack, where Mary has been confined. They free her and, while Cal waits for her kidnapper to return, Don accompanies Mary to town, where she is reunited with her father. When the masked man returns to the shack, Cal struggles with him and discovers that he is Lawson, the only man in town who owns a Sharp's rifle. Lawson reveals that he tried to make the theater fail so that he could buy it cheaply. He kidnapped Mary so that people would continue to believe Beeton was behind the shootings. Now that the mystery is cleared up, the show goes on to great acclaim.