Betty, the daughter of a retired professor and a romantic dreamer, craves excitement and adventure. Captain Tobias Crook, a mariner, seizes upon her longings to induce the professor to finance and accompany him on a lost treasure hunt. Dick Winthrop is very interested in these plans because he is a Secret Service agent on the trail of Crook, who is in the business of promoting these expeditions and then marooning his investors on desolate islands. Living up to his reputation, Crook forces the professor to sign over his property and then leaves him to die on the island. Returning home, Crook and his crew commandeer the professor's house. In the drunken brawls which follow, Crook is killed and the crew decide to assault Betty. As she cowers in her locked room, Winthrop, who has saved her father from the island, comes to the rescue.