In the 1890s, The River Queen , a family-oriented showboat owned by Captain Sam Jackson, docks in the small Mississippi town of Ironville, with a new show featuring actor Dexter Broadhurst. Also on board the ship is Dexter's bumbling but good-hearted assistant, Sebastian Dinwiddie. Just as the showboat arrives in town, gamblers Crawford, Bonita Farrow and Bailey are ordered to leave Ironville by the sheriff. Seeing an opportunity to make some real money, the three arrange to meet Captain Sam at the Gilded Cage saloon in St. Louis, and there wine and dine him. Despite the best efforts of Dexter and Sebastian to save the naïve seaman's investment, the three win controlling interest in The River Queen in a dishonest poker game. Crawford, Bonita and Bailey then set up a crooked gambling operation on the ship, agreeing to leave once Captain Sam pays them $15,000. After one of his customers is shot during a gambling dispute, Captain Sam publicly condemns his partners. Although Bonita warns him that another such outburst will land him and his performers ashore, Crawford begins to have pangs of guilt about his friends's treatment of the showboat performers, as well as romantic feelings for Caroline, Captain Sam's beautiful daughter. Meanwhile, Dexter and Sebastian break into Bailey's room whie he is sleeping to search for Captain Sam's promissory notes, but find nothing. Later, after Sebastian exposes a crooked dice game at one port, Bonita offers to play Captain Sam a single game of poker for the full interest in The River Queen . Unknown to Bonita, Crawford has rigged the deck so that the seaman will win, and in the ensuing mêlée, Dexter and Sebastian manage to capture Bailey and all his men. Bonita and Bailey are then arrested, and as his reward, Sebastian is finally given a role in The River Queen's latest production, playing "Little Eva" in Uncle Tom's Cabin .