Mexican-Irish grandee Don Miguel Arguella, known as "Don Mike," rescues a party of settlers stranded in the desert. Among them are leader Reuben Pettingill, Jason Kelsey and his daughter Mary, to whom Don Mike is attracted. Pettingill learns that Don Mike has neglected to record the boundaries of his estate and files a claim to the greater part of the acreage. The town alcalde, Don Luis Ybara, bears a grudge against Don Mike for interfering with his persecution of Carmen, a servant girl on the estate. When Don Luis is found murdered, Pettingill offers a reward for the grandee's capture. General Frémont hears of the incident and sends a group of soldiers to the rancho, while Don Mike poses as a monk to officiate the wedding of Pettingill and Mary. Don Mike clears the room by attaching daggers to a pair of long ropes and swinging them in circles, then subdues Pettingill. After revealing the villain as a murderer and usurper, Don Mike wins the love of Mary.
—AFI