A successful novelist named Richard Harland meets the beautiful and enigmatic Ellen Berent on a train, and they quickly fall in love. Their whirlwind romance leads to marriage, and Richard is initially mesmerized by Ellen's intense devotion. However, her passionate affection soon reveals a darker side characterized by possessiveness and jealousy. Ellen desires exclusive control over Richard's attention and increasingly isolates him from his friends and family. Her manipulative behavior estranges Richard from his younger, disabled brother Danny and Ellen's gentle cousin Ruth.

Ellen's obsessive love escalates, leading to tragic consequences that profoundly impact the lives around her. Her actions become unpredictable and dangerous, driven by an irrational fear of losing Richard. As the story unfolds, layers of Ellen's troubled psyche are exposed, forcing Richard to confront the reality of her true nature. The psychological tension builds as he grapples with Ellen's alarming capacity for destructive acts, compelling him to seek a way out of the suffocating grip she holds on his life.