Bertie Joyce is a young society chap who is struck on the head by thugs while returning from his bachelor dinner on the eve of his marriage to Dorothy Hardin. His memory completely obliterated by the blow, Joyce wanders down to the riverfront, falls asleep on a wharf and tumbles into the river. Of course Joyce was in evening clothes at the time of the hold-up and the thieves have divested him of his coat and overcoat. When Joyce scrambles out of the water, he removes his dress shirt, wrings it out, finds his tall hat, and ambles into the first saloon with the shirt over his arm. There is a mild sensation in the place when the stranger enters and the inhabitants, it is the headquarters of a band of thieves, are all for throwing him out. But the proprietor's daughter comes to the rescue and the stranger is fed and clothed. Then it is decided that he would make an excellent gentleman burglar, adding "class" to the gang, so he is trained in the art of burgling. The papers are full of the disappearance of young Joyce and the descriptions of the vast assortment of wedding presents over which the near-bride is pictured as weeping. It looks like a rich haul to the gang and Joyce, his identity for a moment suspected, is sent with two others to rob his own fiancée's home. They get inside the house, and when Dorothy interrupts the work, Joyce instinctively shields her from the blow of one of the crooks. The thug attacks Joyce and the two men engage in a desperate battle during the course of which they fall down a flight of eighteen steps. Joyce lands on the bottom at the foot of the stairs and is stunned. The police arrive and a doctor is immediately summoned for Joyce. He declares that a very minor operation will completely restore Joyce's memory, and when it has been performed, Joyce has no knowledge of his excursion into the underworld, but believes that he is simply recovering from the hilarity of his bachelor dinner. If the instructions of the doctor have been carried out, he still believes so, for Dorothy, whom he has married, has solemnly promised never to tell.