Velma, the lighthouse keeper’s daughter, and Clem Curtis, a sailor, are engaged to be married. Clem has one weakness, an appetite for liquor, but he has promised Velma that he will stop. Returning from a voyage he goes to see the girl with the odor of liquor on his breath. This precipitates a quarrel. Later Velma’s father suffers a slight stroke of paralysis while in the tower and she goes in haste to the mainland to fetch a doctor. The only physician in the village has gone away for a week. Meanwhile Dr. Carlson, a retired physician, steams into port on his private yacht. He and Velma meet at the landing and her distraction leads him to offer his assistance and goes with her to attend her father. As he is leaving the lighthouse he is seen by Curtis, who has returned to try to make up the quarrel. Curtis jumps at the conclusion that he has a rival and accuses Velma, who takes quick advantage of the situation. Thinking that by making Clem jealous she may spur him to reformation she refrains from telling him who Carlson is. Curtis becomes insanely jealous and broods over the loss of the girl. He learns that Carlson is a millionaire and the owner of a yacht and thinks that Velma was influenced by the prospect of wealth and position. She, on the other hand, has not the lightest suspicion of the insane passion she has aroused in Clem and only thinks that in a little while he will return to make up. Instead, Clem takes to drink and broods over his trouble. A sailor aboard the yacht quits and Clem learns that the captain is seeking a sailor for Carlson’s crew, plans a scheme for revenge and ships on the yacht. Soon after the yacht sails Clem finds his opportunity. Carlson is alone on deck when Clem creeps up behind him and attacks him. A struggle follows, during which Carlson is thrown overboard. Clem becomes frightened of the consequences and deserts the ship in one of the small boats. Carlson in the water swims toward land, but soon becomes exhausted. When his strength is nearly gone he reaches a buoy off the lighthouse to which he clings. In the lighthouse Velma sees a small object on the buoy and makes out the figure of a man. She goes to the rescue in a skiff and takes Carlson back to the lighthouse. Clem, having landed on a barren shore, is alone with his guilty conscience. He stands the mental anguish as long as he can and then decides to go back to the girl, confess his crime and give himself up. Returning to the lighthouse he finds her and confesses. Instead of being horrified she calms him and calls Dr. Carlson. A reconciliation follows.