Hilda Kreemhild, Joan Bennett, is fed up with her life as a gun moll to gangster Floyd and visits her mother Olga, Peggy Wood, who keeps house for the cultured Randall family. Professor Randall, John Hyams, and his wife go on vacation, leaving behind sheltered son Robert John Hubbard to begin a new, nerve-wracking career as a reporter, nudged by Hilda toward a rough-and-tumble world of headlines and danger.
Soon after, Benny, a feeble-minded flower vendor, tails showgirl Gladys Fontaine, whom Floyd compels to join him on his houseboat to take Hilda’s place, and Gladys, Lilian Bond, finds herself caught in a perilous scheme. Fearing for Gladys’ safety, Benny poisons a cup of coffee intended for Floyd, but Gladys drinks it instead. In a swift, grim moment, Floyd discards Gladys’ body into the river, setting off a chain of consequences that ripple through the waterfront.
The next morning, Robert reads about Gladys’ death and attaches himself to hard-drinking, womanizing ace crime reporter Deakon Maxwell, Adolphe Menjou, and his steadfast photographer, Ed O’Malley, William Gargan. The trio heads to police headquarters, where every bum on the waterfront at the time of the murder has already been rounded up for questioning. Benny confesses to accidentally killing Gladys, but his claim is ridiculed and not believed, leaving the little man feeling even more desperate.
Robert, moved by Benny’s plight, chooses friendship over skepticism and quietly keeps the truth in his pocket—until the moment when he can reveal it. After a night of drinking with Deakon and Ed on Benny’s dime, and learning from Benny that Gladys was thrown from Floyd’s houseboat, the drunken Robert phones his editor, Wilson, and reports the details. Waking up with no memory of the previous evening, he soon discovers that his story has scooped the other papers, catapulting him into overnight fame and the sense that he might actually be a true journalist.
As Floyd realizes that the young reporter has earned a coveted byline, he decides that Robert must be silenced. Floyd’s gang descends on the Randall residence, where he confronts Hilda in a tense clash that tests loyalties and courage. Benny, aiming to protect Hilda, produces more of his deadly coffee, and the night spirals into a chaotic firefight high above the streets. Deakon and Ed, drunkenly firing fireworks from the roof, mistake the gunfire for real attacks, and the gangsters begin to fall one after another, felled not by bravado but by Benny’s poisoned brew.
In the end, the arrival of the police brings a needed rescue, and the danger subsides. Robert’s sensational scoop is vindicated, and amidst the dust and commotion, he manages to win the heart of Hilda, proving that courage, quick wit, and a touch of luck can alter the course of a life tangled with crime, love, and ambition.
