Jim "Mac" McFee Charles C. Wilson tires of running two illegal gambling ships and offers his partner to Ronny Hillyer Frank Albertson, a manager who works on one of the boats, in a bid to solidify a real partnership. Ronny finds himself juggling an uneasy balance—he has to withstand the insistence and flirtations of Gloria Vance Barbara Pepper, the singer girlfriend of his boss, even as he tries to keep the operation afloat.
When a couple of unfamiliar casino patrons draw Ronny’s suspicion, he fears that lookout Tom Braden Jack La Rue may be leaking information. He warns Mac, but the situation spirals quickly out of control. The ship is boarded by the police, and in a tense confrontation, Burdon—who is armed—pulls a pistol. A struggle ensues, and Burdon is accidentally shot and killed by Mac with Burdon's own weapon. Ronny seizes the moment, grabbing the gun and racing out as the police intervene. He dives into the water, escapes the ship, and makes his way to shore, where he disguises his identity to protect both his new partnership and his own freedom.
Wearing sailor clothes, Ronny crosses paths with Joan O'Brien Ann Rutherford and her father, Captain O'Brien J. Farrell MacDonald, an alcoholic gambler who often finds himself drawn into the wrong crowd. To avoid capture, Ronny hides in Alex's home—Alex Victor Potel being a fisherman who is away for a spell. Pretending to be Alex’s friend named Bill, Ronny grows closer to Joan, and the two begin to fall in love. He phones Mac with a plan to flee to South America, but first he must navigate the danger surrounding his past deeds.
Captain O'Brien still drags Ronny to a craps game, where Ronny’s own skill with dice helps him win a hefty sum of money. Tod [Grant Withers], a neighbor and would-be suitor of Joan, discovers the winnings and tells Joan, initially souring her view of Ronny. Yet Ronny’s generosity shines through: he returns the money he wins, placing it in the O’Briens’ book, and also sends Tony Spadaloni [Paul Porcasi] a monetary boost when his wife, Mrs. Spadaloni [Mathilde Comont], loses her husband’s stake in a game. Tod begins to sense that Ronny might be the very man the police are seeking, and when Alex later returns, Tod tries to reintroduce him to his “friend,” a move that culminates in Ronny saying farewell to Joan. Ronny manages to slip away, still determined to protect those he has come to care about.
With time running out, Ronny makes another call to Mac to reveal his hiding place, only to find Gloria at the other end—Gloria wants to come see him, but she doesn’t tell Mac. Mac follows and—recognizing that Ronny will never betray him—decides to stand by him and arrange for a freighter to smuggle Ronny out of the country. Mac even takes the murder weapon, intending to hide it. Ronny insists on one last visit with Joan, hoping to hold onto the life they might have together.
Yet Gloria proves dangerous, and she betrays their location to the police. Mac and Jess, his loyal aide Ward Bond, hire goons to confiscate the couple and bring them to justice. A scuffle erupts when Tod spots Ronny with Joan, and the police close in on both Ronny and Mac, with Mac clutching the pistol. In a candid moment, Mac confesses that he killed Burdon in self-defense, a revelation that redefines their fates. The revelation clears the way for Ronny and Joan to pursue their shared dream: opening a restaurant where they can build a life away from the gambling ships that once defined them.
