At the King Rubber Company building in New York City, Alfred King, Jr. tells his father, the company president, that too many old men are running their overseas plantations with outmoded management practices. Meanwhile, at the King plantation in the Amazon, Jim Conway invents a new way to make rubber harden faster. When Jim prepares to meet his American fiancée Laura in a seaport at Los Cedros, his kindly boss, Davis, warns him that the company does not encourage their men to marry because most women cannot bear living in the jungle. At Los Cedros, Jim receives a wire from Laura calling off the wedding and dreads the embarrassment of returning to the plantation without a wife. He gets drunk and meets nightclub entertainer Joan Madison, who, eager to avoid a detective named Maguire, agrees to pose as his wife for $500. At the plantation, Joan and Jim fall silently in love with each other. Then Jim learns that the company has accepted his new process but will be calling it the "King Process," denying him any credit. Soon after, Davis receives word that he is to be replaced and shoots himself. Joan, enraged at the injustice of the workers' unrewarded loyalty, chastises Jim for not asserting himself with the company. Rita, a native who is married to plantation worker Tom Marshall, explains to Joan that the company provides the sole source of income for her people. Joan then confesses to Rita that, although she now loves Jim, initially she was only posing as his wife because she got into trouble in the United States. Later, Joan offers to give Jim back his $500 and tries to tell him her secret, but he professes his love and assures her he does not want to know. The Kings visit the plantation to announce that Junior is going to take over Davis' position, which Jim had wanted. When Jim explains that the men were loyal to Davis and would balk at taking orders from an inexperienced stranger, Junior insults Davis by calling him weak-natured. Jim knocks Junior out and is fired. Joan, however, secretly meets with King, Sr., and by lying that she registered the Conway Process for a patent, gets King to make Jim plantation boss at the salary he was going to pay his son. Maguire arrives and convinces Joan to return to the States and stand trial for murder rather than ruin Jim's good reputation. Joan finally confesses everything to Jim, but tells him she is innocent and was merely protecting someone. Jim assures her their marriage means everything to him, but she pretends to be cold toward him so that he will allow her to leave. The next day when Joan boards the boat with Maguire, however, she finds Jim onboard. He has taken a leave of absence in order to help clear her name.