Ivy

Ivy poisons Jervis to escape her marriage and pursue a wealthier life with Miles Rushworth. She views her husband's lack of prospects as an obstacle to the luxurious lifestyle she desires. After Miles refuses to pursue a relationship with her because she is married, Ivy decides to remove the marriage obstacle permanently by murdering Jervis and framing Dr. Roger for the crime.

Earlier in the film, Ivy despairingly complains about Jervis's poor prospects while fixating on Miles's wealth.

Miles is attracted to Ivy but refuses to pursue a relationship because she is married to another man. After they share a brief kiss in the dark, he apologizes and declines any further involvement, stating that social propriety and loyalty to her husband constrain him from acting on his feelings.

Miles demonstrates his moral stance early by maintaining that he will not pursue a married woman.

Roger confesses to Jervis's murder out of twisted devotion to Ivy. Although he is innocent, he is so infatuated with her that he willingly accepts blame for the crime, believing he is sacrificing himself to protect her. This devotion is exactly what Ivy counted on when she framed him.

Throughout the film, Roger demonstrates his intense infatuation with Ivy, making him vulnerable to her manipulation.

Ivy poisons her husband Jervis and deliberately leaves evidence pointing to Dr. Roger, who was having an affair with her. She calculates that Roger's involvement in her infidelity would provide sufficient motive for the police to suspect him of the murder, allowing her to eliminate both her husband and her lover while clearing the path to Miles.

Ivy's affair with Roger was ongoing throughout the timeline, giving her the means to plant evidence linking him to the crime.

Inspector Orpington remains skeptical of Roger's confession from the beginning. He tells Jervis's mother that he believes Roger is sacrificing himself for Ivy, not genuinely guilty. The inspector recognizes the inconsistencies in the case, particularly Ivy's wealth ambitions and the convenient timing of the murder, and continues investigating despite Roger's confession.

The inspector's initial investigation scrutinizes motives, including Ivy's desire for wealth and freedom.

New evidence surfaces during the investigation that challenges Roger's guilt and prompts a reevaluation of the case. This evidence exposes who was truly manipulating the outcomes and redirects suspicion away from Roger. His lawyer then informs Ivy that Roger is free, marking a turning point in the legal proceedings.

Inspector Orpington's continued investigation into inconsistencies in the case leads to this breakthrough.

After Miles learns of Ivy's scheming and walks out on her, her entire plan collapses. Distraught and unable to face the consequences of her actions, Ivy flees her apartment in panic. In the chaos of her escape, she falls down an empty elevator shaft, meeting a tragic end that mirrors the collapse of her criminal schemes.

Miles's departure represents the final abandonment of Ivy, leaving her with no one and no way out.

Ivy attempts to persuade her husband Jervis to divorce her first, hoping to legally end the marriage and become free to pursue Miles. However, Jervis refuses to grant her a divorce, leaving her trapped in the marriage. This rejection pushes Ivy toward the more desperate solution of murdering her husband.

Ivy's initial fixation on Miles as her ticket to a better life precedes her divorce attempt.

Once Roger's lawyer informs Ivy that he is free, her leverage over the situation evaporates. She no longer has control over the narrative, and the truth begins to surface. When Miles learns of all her schemes, her affair, her murder of Jervis, and her attempt to frame an innocent man, he abandons her. With her plans completely unraveled and no one left to turn to, Ivy is driven to flee and ultimately meets her death.

The moment Roger is freed marks the turning point where Ivy loses all power.

Ivy is primarily motivated by wealth and social status. While she maintains an affair with Dr. Roger, she sees him as merely a lover, not a viable long-term prospect. Miles Rushworth represents the wealthy, luxurious life she desperately desires. She views Miles as her ticket out of her dull marriage and into a life of opulence, making him her primary target despite his moral objections to her marriage.

Ivy's initial discontent stems from her dissatisfaction with her husband's modest prospects.