"Big John" McMasters (Gable) and "Square John" Sand (Tracy) are two down-on-their-luck oil wildcatters who join forces. Without enough money, they steal drilling equipment from a skeptical Luther Aldrich (Morgan). Their well proves a bust and they have to hastily depart when Aldrich shows up with the sheriff to take back his property. The two oilmen team up and make enough money to partially pay Aldrich. To get him to back them for a second try, they cut him in for a percentage of the well. This time, they strike it rich. When Elizabeth 'Betsy' Bartlett (Colbert) shows up, McMasters sweeps her off her feet (without knowing that she is Sand’s girl) and marries her. Sand accepts the situation, wanting Betsy to be happy. However, on their first anniversary, she catches her husband dancing with a barroom floozy. As a result, Sand quarrels with McMasters and they flip a coin for the entire oilfield. Betsy leaves too, but returns when she learns that her husband has lost almost everything to Sand and needs her. Each man goes through booms and busts. Building on his renewed success as a wildcatter, McMasters moves to New York to expand into refineries and distribution, competing against former customer Harry Compton (Lionel Atwill). Seeking inside information about his rivals, he hires Compton's adviser Karen Vanmeer (Lamarr), who uses her social contacts and womanly charms to gather industry gossip. Sand sees that McMasters is getting too close to his employee. Sand tries to buy Vanmeer off, even offering to marry her, but she declines. When a miserable Betsy tries to commit suicide by taking sleeping pills, Sand decides that the only way to help her is to bankrupt McMasters. However, Sand loses his costly battle with his former friend and goes broke. It is only when he asks McMasters to give his wife a divorce that the married man finally comes to his senses. Later, McMasters is prosecuted by the government for violating the Sherman Antitrust Act and loses his busine...