Damn Yankees is about a fanatic, middle-aged, Washington Senators' fan who keeps glued to his T.V. set during the baseball season. The distraught real estate agent rants against the Yankees who are clobbering the league's clubs, including his beloved Senators. In an impulsive oath, he says he would sell his soul if he could just stop those Yankees. A happily cynical Devil appears and the fan is transformed into something the Senators need: a young, phenomenal, long-ball hitter.
Joe Boyd becomes Joe Hardy, the sensation of the leagues, leading his team as they rise in the league standings. This newcomer with his success is the target for speculation by the press. As a safety precaution to keep Joe in line and to cure his unexpected loneliness for his wife, the Devil introduces Joe to Lola, his prize powerful weapon. However, when the Devil is ready for Joe to live up to his end of the bargain, Joe outwits him in the final moments of the big game.