Lina McLaidlaw, a shy and wealthy woman, meets the charming and charismatic Johnnie Aysgarth on a train. Despite her father’s reservations, Lina falls in love and quickly marries Johnnie. It isn't long before she discovers that Johnnie is irresponsible with money and has a penchant for gambling. Her unease grows when Johnnie's lies about his financial stability come to light. Matters take a darker turn when their friend Beaky dies under suspicious circumstances during a business trip with Johnnie, raising Lina's doubts about her husband’s intentions.

As Lina's suspicion melds with fear, she is increasingly convinced that Johnnie may be plotting to kill her for her inheritance. She becomes more isolated, tormented by thoughts of betrayal and impending danger. Lina's attempts to confront Johnnie lead to more evasions and cryptic answers, further deepening the chasm of mistrust between them.