Among the curios brought from India by Colonel Marsden is a black pearl. Margaret, his daughter, fancies the jewel and asks for it, but father replies that it is an occult jewel and can only be possessed by one showing supreme faith. Phil, the colonel's nephew, is heavily in debt to Benson, a gambler. Benson renews his importunities for his money and finally forces Phil to introduce him into Colonel Marsden's family as a friend. Benson inveigles Phil into more gambling games. Phil finally agrees to Benson's proposal that they rob his father's safe and put the blame on someone else. In the meantime, Jack North, who is friendly with Margaret, fears he will lose her because of the fascinations of Benson. To humor her he again asked the Colonel for the black pearl for Margaret, but the Colonel refuses. Returning home North writes to Margaret telling her of his failure to get the pearl, but adding that he "will get it yet." Benson and Phil steal the keys from the Colonel and rifle the safe. North is decoyed to the house by a note with Margaret's signature forged. He is assaulted by Benson and Phil and is carried, bound and gagged, into an unused room in the house. The unmailed letter to Margaret is found in North's pocket and this with the keys are placed in front of the safe. The robbery is discovered. The police fail to find North, who, of course, is suspected. In the attic above, his muscles bound. North crawls to the washstand. He bursts the faucet with his feet and with his heel blocks the drain hole. Rapidly the water rises, flooding the floor. A maid, in the room below sees the ceiling dampen and then the rush of water falling in cascades about her. She notifies the police who are in conference with Colonel Marsden at whose side sits Margaret, stoutly defending her absent lover and declaring her implicit faith in his innocence. In the library, Benson and Phil, realizing by the commotion above, that North has been found, stand indecisively. Benson makes a break for the balcony with Phil close behind him. But Benson's revolver stares at Phil sinisterly. Determined that Benson shall take the medicine with him, Phil grapples with him. The police, breaking in upon North, find him nearly submerged in the rising flood. Asked to explain. North says that the Colonel's nephew can best do that. A shot from Benson's revolver aimed at Phil, but diverted by the latter's quickness, attracts them below. The struggle is still on with Benson gradually wearing down his opponent when the police pull him off. Phil confesses. Not long after the Colonel approaches North and Margaret and hands to Margaret the black pearl.