Because of his bad temper, Jimmy Duncan is sent by his uncle George to work at Tom Kirk's ranch for a one-month probation period. Under George's stipulations, if Jimmy is involved in one fight during that time, he will be disowned. Jimmy works as assistant to Kirk's daughter Laura, and the combination of this work and Jimmy's refusal to fight causes the ranchhands to tease him. Laura's boyfriend Nobro is a teller at her father's bank and uses his position to run a scam on the bank as head of a gang of outlaws. He tries to get rid of Jimmy by having the outlaws pick fights with him, but Jimmy remains steadfast. When Mr. Gonzales withdraws $3,000 cash from the Kirk bank, Nobro signals one of his men to steal the money. Later Jimmy and ranchhand Stubby find Mr. Gonzales unconscious and another man dead. Jimmy discovers the robbers' hideout, but they elude him and leave Stubby hanging from a cliff. After Jimmy rescues Stubby, he tells him about his probation and they become friends. Nobro, who is really interested in acquiring the Kirk fortune, plans to rob the bank the night of a dance if Laura does not accept his marriage proposal, and gives his men keys to the bank's entrance. Stubby and Jimmy arrive late for the party, and noticing lights on in the bank, go in to investigate. They discover the thieves in the vault and fight with them. Meanwhile, Laura accepts Nobro's proposal and while she tells her father, Nobro signals the bank to stop the robbery. When he fails to receive a response, he goes to the bank and Jimmy captures him. Nobro yells for help and the entire party rushes over. Nobro tells Kirk he caught Jimmy in the middle of a robbery, but when Kirk opens the vault he finds Nobro's thieves inside. They identify Nobro as their chief and all are arrested. Jimmy proposes to Laura and she accepts.