Millionaire John Duncan is dying from an illness which cannot be cured. He plans to divide his fortune between his cousin, lawyer Robert Waldo, who has taken him in during his sickness, and Dr. David Graham. David considers Duncan his mentor, although, unknown to him, Duncan is actually his father. Waldo convinces Duncan to leave all his estate to David in a plot to get the money along with Duncan's nurse, Jane Chase, who loves David. Waldo, who has a smiling face and apparently benevolent personality, has a hateful, treacherous soul. He plans to frame David by giving him a motive for a murder that Waldo will commit. Now a hopeless invalid, John asks David to end his suffering, but David refuses to give him the necessary medication, so Waldo decides to help John die to suit his own purposes. At Christmas, Waldo invites David to a party for orphans, asking him to play Santa Claus. Instead, David sends Wilfred Morgan, an idle tramp, who becomes drunk and disappears. Left alone with Duncan, Waldo gives him an overdose of the drug David had prescribed, believing he is committing the "perfect crime." However, Morgan recovers sufficiently to see what is happening. When David is arrested and tried for murdering John, Waldo offers to defend him, but presents a very poor defense, hoping that the jury will convict David and sentence him to die. David instead receives a life sentence, and while Waldo is awarded John's estate due to David's disqualification, the land is unobtainable while David is still alive. Waldo secures David's release by forging a suicide note left by John, then decides to kill the young man himself. Waldo must first deal with Morgan, however, for the tramp has used his knowledge of the murder to blackmail him. Waldo runs Morgan over with his car, but the injured man reaches Jane and tells her of Waldo's schemes before he dies. Meanwhile, Waldo has enticed David into his cellar, where he intends to asphyxiate him by surrounding him with candles that will use up all of the oxygen. Jane rushes to Waldo's house and shoots him when he fails to reveal where David is. The police arrive in time to save David, and Waldo dies realizing that people cannot be manipulated like pawns in a chess game.