A beautiful neurotic will stop at nothing to hold onto her husband's love.

When author Richard Harland is released from prison after serving a two-year sentence, he goes to Deer Lake, Maine, and is met by his attorney, Glen Robie. Glen sends Richard off in a waiting canoe to Richard's lodge, "Back of the Moon," then relates his story to a companion: A few years earlier, while Richard is working on a new novel, he accepts an invitation from Glen to vacation at his ranch in Jacinto, New Mexico. During the train ride, Richard is left breathless by the striking beauty of a woman who comments on his close resemblance to her late father. Richard is then greeted at the station by Glen, who reveals that the beautiful woman, Ellen Berent, is also visiting the Robie family with her mother Margaret and adopted sister Ruth. During dinner, Ellen tells Richard that they have come to scatter her father's ashes at his favorite spot in the mountains, which he used to describe as "the front lawn of heaven." Richard follows the Berents when they depart in the morning and is fascinated by Ellen's demeanor as she scatters the ashes. The next day, when Richard confesses to Ellen that he questioned Glen about her fiancé, attorney Russell Quinton, she coolly declares that she has taken off her engagement ring. The next night, Russell comes to the ranch, having received a telegram from Ellen breaking their engagement, and Richard is astonished when Ellen announces that she is going to marry him. Despite his misgivings, Richard cannot resist Ellen and the couple are married. After a brief honeymoon, the newlyweds travel to Warm Springs, Georgia, where Richard's beloved, teenaged brother Danny is recovering from polio. Ellen's fanatical devotion to Richard begins to surface when she refuses to hire servants, stating that she wants to do everything for him, but Richard is touched by her attentions to Danny. Ellen's coaxing prompts Danny to walk with crutches, and soon the boy is accompanying Ellen and Richard to Back of the Moon, even though Ellen had asked Danny's doctor to order him to remain in Georgia. At the lodge, Ellen is frustrated by the presence of Danny and Leicke Thorne, an old family friend, and resents the time that Richard spends writing. Ellen is infuriated when Margaret and Ruth show up at the lodge, and Richard is appalled by his wife's hostility toward her mother and sister. Ellen even accuses Richard of being in love with Ruth, then tearfully begs for his forgiveness by telling him that she cannot bear to share him with anyone else. Margaret and Ruth leave soon after, and one afternoon, Ellen accompanies Danny on his daily swim in the lake. Ellen follows in a rowboat behind Danny and urges him on, but when a cramp hits the exhausted boy and he cries for help, she watches impassively as he drowns. Richard seems to accept Ellen's explanation that Danny's death was an accident, but as time passes, he becomes mired in a deep depression. Hoping to rejuvenate Richard's love, Ellen becomes pregnant, and Richard eagerly anticipates the birth of their child. The couple have moved to the Berent home in Bar Harbor, and as her pregnancy progresses, Ellen comes to loathe the baby and fears that it will come between her and Richard. After telling Ruth that she longs for "the little beast" to die, Ellen throws herself down a flight of stairs and causes the death of her unborn baby. Upon Ellen's return from the hospital, Ruth is unable to bear her sister's malevolence any longer and prepares to leave for Mexico, which is the setting of Richard's just-published novel. Furious that the book is dedicated to Ruth and not to her, Ellen confronts Richard and confesses that she murdered Danny and their baby. When Richard leaves her, Ellen concocts an elaborate scheme to frame Ruth for her "murder," then kills herself with arsenic. Ruth is brought to trial by Russell, who is now the State District Attorney, and Ellen's careful plans, including asking Richard to scatter her ashes with her father's, stack the evidence against Ruth. While she is being questioned, Ruth admits to being in love with Richard but maintains her innocence. Unable to let Ruth suffer, Richard takes the stand and reveals the depths of Ellen's jealous depravity. The story almost completed, Glen tells his friend at the lake that while Ruth was acquitted, Richard was sentenced to two years in prison for being an after-the-fact accessory to Ellen's unreported crimes. As Glen finishes the tale, Richard paddles up to the cabin, where Ruth welcomes him with a loving embrace.