Missionary Curtis Powell returns to the United States and visits his brother Frank, who sells stock in the International Oil Securities Co. Curtis cautions Frank against taking hard-earned money from poor people, but Frank believes in the company and has invested his own money, which he will use to get married when the company's wells now under construction in South America are brought in. Frank introduces Curtis to his fiancée, Marjorie Norton, and after sending them off to prepare dinner, he is visited by elderly Mrs. Hardy, who brings him proof that the wells are not being built. He questions the company's owners, William E. Carlton, George Richards and Burns, but despite their assurances, Frank insists on investigating the oil field. After Frank leaves, Carlton despairs because he and his partners have lost the company funds in the stock market. Richards and Burns do not regret their embezzlement, however, and that night, after Carlton kills himself to avoid disgrace, they frame Frank for murder, so that they can collect Carlton's life insurance. Frank is arrested after Carlton's body is found in his apartment, and is convicted and sentenced to death. While being transported to the penitentiary, Frank meets hoodlum Gabby Hoke, who takes Frank along when his gang helps him escape. Frank then goes to Richards' and Burns's apartments, where they admit their guilt. Curtis arrives and convinces Frank that they need solid evidence, and they escape. Frank and Curtis go to the gym owned by Sparks, the leader of Gabby's gang, but while they are there, police detective Ryan arrives and questions Sparks. In order to distract Ryan, Curtis spars with Sparks's champion, Roundhouse, and accidentally breaks his jaw. After Ryan leaves, Sparks tries to cancel the fight between Roundhouse and the fighter belonging to Tony Maroc, the gangster who helped Richards and Burns frame Frank, but Tony insists that the fight be held. Sparks, using Frank as a hostage, convinces Curtis to take Roundhouse's place and Curtis begins training. Tony sends one of his molls, Helen Vincent, to distract Curtis, but when she fails, Tony engineers Curtis' arrest for aiding Frank. Sparks, who has been won over by Curtis' sincerity, organizes his gang to prove Frank's innocence and thereby free Curtis. They establish that Carlton was killed elsewhere before being dumped in Frank's apartment, then go to the company office, where they find evidence linking Tony's gang to the frame-up. Later that day, Richards and Burns discover the dictaphone cylinder on which Carlton left his suicide statement and destroy it. Just then, Ryan enters, shows them a statement from Tony that they are Carlton's murderers and arrests them. Having destroyed the cylinder, Richards and Burns have no proof that Carlton committed suicide, and they are arrested. Frank is cleared, and soon after, he and Marjorie leave on their honeymoon trip, while Sparks bids Curtis a fond farewell.