Ex-prizefighter Joe Anton owns the "55," a New York speakeasy that was once the Healy family mansion.  Seeing Jerry Healy sitting alone in the club night after night, Joe becomes enamored of her and, resolving to get into a legitimate profession, dumps his girlfriend Iris Dawn and takes lessons in manners and "class" from the matronly Mabel Jellyman.

Joe arranges to have dinner with Jerry, whom he calls "Miss Healy," but also invites Mrs. Jellyman to keep him from making a fool of himself.  The dinner is interrupted by Maudie Triplett, Joe's old mistress, whose sharp wit and double entendres embarrass Joe, but amuse the ladies.  During a tour of the house, Iris pulls a gun on Jerry in Joe's bedroom, but Joe distracts her and saves Jerry, who kisses him and calls him the "pirate of the day."

Meanwhile, mobster Frankie Guard wants to buy Joe's club because it is cutting into his own business, but Joe refuses to sell until he sees his chances with Jerry increase.  He goes to Jerry's apartment to swear his love, but she tells him that she plans to marry the wealthy Dick Bolton, whom she does not love, to bolster her family's lost fortune.  Calling Jerry "just another girl in a skirt," Joe leaves, disillusioned.

That night, Frankie and his men arrive at the "55" to close the deal, but Joe reneges.  In an attempt to deny her true feelings for Joe, Jerry arrives at the club and begins to wreck his bedroom, until he grabs her and kisses her.  She rebuffs him until Frankie's mob arrives and starts shooting and she realizes that to save his life, she must admit her love.  Finally the two embrace and Joe gives up his club to Frankie.