As a deadly spotted-fever epidemic rages in the jungle, the owners of the Rothmore Mines implore Dr. "Pop" Fahrenheim, the leading scientist at the Rothmore Institute, to leave New York and travel to the jungle for two years to find a cure. His assistant, Chris Claybourne, the playboy son of the famous Dr. Claybourne, agrees to go with him, but wants a two-week fling before the trip. At a crooked gambling club run by "Fish-Eye," Chris loses five thousand dollars on credit. That same night he meets model Rita Wilson, who has refused Fish-Eye's proposition that she lure wealthy escorts to his gaming tables for a percentage. Though they are strongly attracted to each other, Chris and Rita agree not to fall in love, but spend his spree together, having fun and swiping unusual hats. As Chris's departure day approaches, however, they realize that they are in love and Chris promises not to go to the jungle. That same night, Fish-Eye forces Chris to sign a check for his debt, and gives him until the next afternoon to make it good. As Dr. Claybourne's money is all used to support his hospital, Chris' only hope is his staid brother Tom. When Chris takes Rita to meet Tom, however, Tom tells his brother that he will only help him if he goes to the jungle and waits to marry Rita, whom he considers socially inferior, until he returns. Rita, enraged, tells Chris that they are through and secretly goes to Fish-Eye to arrange to pay off Chris' debt by working for him. Some time later, while Chris waits in vein for letters from Rita, Tom goes to Fish-Eye's club and sees Rita. She then admits that she was the person who secretly paid the debt, but lies and says that her grandmother left her the money. She engratiates herself to Tom by telling him how right he was and "confessing" that she merely had a crush on Chris. On Christmas Eve, Chris suddenly returns to New York on a leave-of-absence and learns that Tom has broken with his fiancée and has just been asked to resign from the hospital for neglect of duty. Though Dr. Claybourne does not know what has happened to Tom, Tom privately tells Chris that he fell in love with Rita and secretly married her, after which she laughed at his stupidity and refused to see him. Now believing that Tom's original opinion of Rita was true, Chris goes to Fish-Eye's club and finds her. She confesses her mistakes and is remorseful, and, because she still loves Chris, agrees to his plan that she accompany him back to the jungle, on a platonic basis, to wait for Tom to agree to a divorce. Several months later, when Chris finally receives word from his father that Tom has obtained his divorce and has gone back to work, Rita is ecstatic until Chris bitterly reveals that this was all part of his plan to get back at her. Though Pop tells him what a fool he is, he sends her away, and refuses her offer to let them test their new serum on her. Pop has been ordered to leave by the local government, but he and Chris go to a remote part of the jungle to test their serum on Chris. Suddenly worried about injecting Chris with the disease, though, he breaks the bottle of serum to delay the test. When Rita learns what they are about to do, she rushes to them and secretly injects herself with the disease instead, because she has nothing to live for. Now realizing he still loves Rita, Chris works feverishly to make more serum. Soon Chris and the recuperated Rita marry and sail back to New York. As he wistfully eyes the captain's hat, Chris promises Rita that when they return to the jungle to build a hospital, he will let her be a part of his work.