Two men quarrel about the design of an aircraft engine and go their separate ways, each attempting to prove the other wrong by winning an aircraft race with his own version of the design. The son of one of the men, who has been serving in the Air Mail Service, goes to work for his father's rival and falls in love with the rival's daughter. The children together design an engine incorporating elements from both of the rival designs and enter it in the air race, easily winning. The children's love and accomplishments reunite their parents.