On 31 December 1928, Waldo Winchester, a reporter, enters Mindy’s restaurant looking for a story and comes upon the “Brain,” a crime boss, treating John Wangle, a young penniless hillbilly and his two bloodhounds to a meal. He is surrounded by his bodyguards, "Crunch” Sweeney and Sam “The Skate,” as well as “Regret,” a gambler, who stuffs sausages into his pockets. Across the room, “Red” Henry, a two-bit hood, is dining with Harriet MacKyle, a socialite who is infatuated with criminals. Harriet loses all interest in Red when her gigolo, Handsome Jack, and his bald friend, Basil Valentine, enter. Jack ignores Harriett and smiles at “Lovey" Lou, a showgirl, who dines with Miss “Missouri” Martin, a speakeasy owner. Winchester takes a seat with “Feet” Samuels, a depressed gambler who is too poor to tell Hortense Hathaway, another showgirl, that he is in love with her. He complains the only reason he has not killed himself is he owes Brain a hundred dollars. Then to Winchester’s surprise, Feet takes out a roll of bills and pays off Brain. Marvin Clay, a millionaire, enters and attempts to flirt with Lovey. Regret rushes over to report seeing Clay smooching with her sister earlier. The two men get in a fight and are thrown out of the restaurant. “Widow Mary" comes in selling roses for a nickel. Brain pays her five dollars for three and is touched by her show of gratitude. As he leaves the restaurant, a man stabs him in the chest and runs off. Brain, fearing a gang war, instructs Crunch and Skate to take him home. Meanwhile, Basil is outside telling bystanders about the stabbing when police Inspector McNamara arrives and detains him for questioning. When McNamara drags Basil to a murder scene, he is irate to see “Doc” Bodeeker, a disgraced surgeon, examining the body of Marvin Clay. Bodeeker pronounces the millionaire dead as the result of a gunshot wound to the chest. McNamara is stumped on how to proceed, until Basil suggests using John Wangle’s bloodhounds to track the killer. Across town, Brain’s wife refuses Crunch and Skate’s pleas to allow Brain in his house, claiming she is throwing a New Year’s Eve party for “respectable” people who cannot afford to be part of a scandal. Brain orders them to take him to his girl friend’s. Skate asks “which one?” Meanwhile, Feet wins diamond earings, a necklace, a bracelet and a large sum of money in a crap game. Regret suggests they hit the racetrack the next day, but Feet explains he sold his body to Doc Bodeeker for a medical experiment, and must commit suicide by morning. He waves off Regret's protests, stating that he has never welched on a deal in his life. Regret follows him to a party at Harriet MacKyle’s and telephones Winchester for help. After he gets reporter Waldo Winchester to agree to come over, Regret is accosted by Lovey, who is infuriated that he never called her after a night of lovemaking. Regret explains he lost all his money at the track and was too embarrassed to call, but she refuses to forgive him. Meanwhile, Feet finds Hortense and showers her with the diamonds he won. While she shows off her jewels, Feet talks Regret into going to a poker game, where he wins that jackpot, including an engagement ring. Shortly after he leaves, the bloodhounds arrive with McNamara, following the scent of Clay’s killer. Back at the party, Winchester and Missouri tell Harriett that Basil is a big-time criminal. When she shows interest in the little man, he pretends to be a cold-blooded killer. Feet arrives and presents Hortense with a diamond brooch. As they kiss, the clock strikes nine and she tells him she must leave for her show, but makes him promise to meet her at the speakeasy by midnight. Feet finds Doc Bodeeker and offers to pay him four times what he got for his body, but Bodeeker refuses. Reluctantly, Feet goes to jump off a bridge, but finds the engagement ring in his pocket and decides to live. Meanwhile, Maud Milligan arrives at Harriet’s party and thinks her fiancé, Crunch Sweeney, has stood her up. She bemoans her fate to Regret who is shocked when Maud accepts his offer to make love. Lovey Lou watches them leave and falls crying into Missouri’s arms. A drunken “Handsome” Jack appears, announcing he is there to “satisfy the hostess.” However, Harriett is enraptured by Basil and orders Handsome Jack to fetch them drinks. When Red Henry laughs at him, Jack punches him in the face. The clock strikes midnight and Handsome can find no one to kiss. When Harriet’s prize parrot squawks, Handsome Jack pulls out a gun and shoots it. Distraught, Harriett orders everyone out of her home and offers herself to Basil if he will shoot Handsome Jack. Meanwhile, Crunch and Sam haul a bleeding Brain from girl friend to girl friend, as they all refuse to harbor him. They exit one apartment to find their taxi driver has left them standing in a snowstorm. Widow Mary steps out of her basement apartment and order them to bring Brain in, then places him in the same bed as her ill son. Across town, Regret has finished making love to Maud who eats the sausages he took earlier. Regret wishes her a happy New Year and goes to the speakeasy. There, he is confronted by Lovey who tells him she never wants to see him again. Nearby, Hortense confesses her love for Feet and he decides to “welch” on his deal with Doc. Back at Mary’s, Brain revives and Skate tells him that Mary used the money Brain gave her to buy the boy some medicine. Another doctor arrives and tells Brain to put his affairs in order and Brain tells Crunch to get him his lawyer. Meanwhile, Basil agrees to pay Handsome Jack one thousand dollars to stage a fake shooting to induce Harriet to fall for him. He rents a pistol from Red who insists it is loaded with blanks. Over at Maud’s, Wangle’s bloodhounds burst in while she is taking a bubble bath. She refuses to say who was with her earlier. Before McNamara can beat it out of her, the hounds catch Regret’ scent and take off. At Bodeeker’s, Feet informs the doctor that he intends to renege on their deal. The physician chases Feet outside with a meat cleaver. At the speakeasy, Harriet watches Basil confront Handsome Jack and, as pre-arranged, pulls his gun and fires. Both men are shocked to discover the gun is loaded with real bullets. The shot misses Handsome Jack and grazes Lovey’s arm, causing her to faint. Regret kneels over the wounded girl and promises God he will give up gambling if he lets her live. Lovey opens her eyes and tells him to add that he will never touch Maud and they embrace. Missouri orders the show to continue. The girls get on swings and sail over the audience, until Feet runs in, chased by Doc with the meat cleaver. Hortense knocks Doc unconscious. Feet confesses he sold his body to buy Hortense a few nice things and she declares her love for him. McNamara, McGinty, Wangle and the hounds burst in and arrest Regret for the murder of Marvin Clay. Lovey takes Winchester aside and confesses she shot Clay for seducing her sister. Just then, Marvin Clay walks in, still alive, clears Regret, and refuses to say who shot him. Just before dawn, Harriet and Basil make plans to run away to England. Regret asks Lovey to marry him and Feet gives Hortense the engagement ring. Hortense gives Feet back all the other diamonds, telling him to sell them so they can start a family. Crunch enters the club and sees some of the girl friends who refused to help Brain. He announces Brain died and left all his money to Widow Mary for taking him in, then asks if anyone has seen Maud. Regret tells Winchester he has to leave before Crunch hears about the bloodhounds tracking him to Maud’s. Winchester suggests he take Lovey Lou with him and the two run off to find a chapel.