A Blueprint for Murder

Cam Cameron arrives at City General Hospital and learns Polly, Lynne's stepdaughter, is suffering violent convulsions from an unknown illness. Doctors initially suspect tetany, but Polly's condition fluctuates; she later seems to recover, then relapses and dies. The medical team struggles to determine the cause of death.

Polly dies, and the doctors cannot determine the cause, leaving Cam with a painful mystery. The lack of answers drives Cam to seek any clue that could explain Polly's death.

Amateur sleuth Maggie, the wife of Cam's lawyer Fred, notices similarities between Polly's symptoms and the pattern seen in strychnine poisoning cases. Cam begins to suspect a connection to the circumstances surrounding his late brother's death. He hesitates to accuse Lynne because of the feelings he's developed for her.

Fred reveals that Cam's brother's fortune would pass to Lynne only if both Polly and Cam's children die, providing her with a credible motive for murder. Cam realizes why Polly and his brother's deaths might be linked to Lynne's interests. The revelation deepens the tension and the need to uncover the truth.

Cam requests an exhumation of Polly's body to allow chemical testing for poisons and to look for signs of strychnine. He insists that definitive testing be done so the truth about Polly's death can be established. The process raises questions about evidence and the credibility of the findings.

The police charge Lynne with Polly's murder, and she is brought before a judge. The judge dismisses the charges for lack of evidence, allowing Lynne to go free for the moment. Lynne then announces that she will take Doug to Europe for a year, prompting Cam to devise a plan to protect the boy.

Cam visits a local store to learn about strychnine and other insect poisons. He learns that there is a potent insecticide with enough strychnine to kill a horse, identified by a distinctive 'W' marking. He purchases a bottle of arsenic poison as part of his plan.

Cam secretly boards the ocean liner bound for Europe in an attempt to stop Lynne from fleeing with Doug. He pretends to romance Lynne to hide his true plan, while internally struggling with whether he should kill her to save the boy. The tension of the voyage weighs heavily on him.

Cam secretly searches Lynne's belongings and finds several pills marked with 'W' intermingled with aspirin tablets. He interprets this as evidence that Lynne may have poisoned Polly and his brother, strengthening his resolve to test her reaction on board.

In Lynne's stateroom, Cam dissolves one 'W' tablet into her drink and tells her that the drink is poisoned and that she must seek medical help immediately. Lynne denies any wrongdoing, insisting the pills are merely aspirin. The moment marks a dramatic test of Cam's suspicions.

The ship's detective reveals himself and assists in the confrontation, and Cam finds himself confronted with the consequences of his planned crime. Lynne's nervous denial clashes with the unfolding evidence, and the clock passes the point Cam expected the poison to incapacitate her. The tension peaks as the truth remains unsettled.

Shortly after Cam and the detective leave, Lynne rushes to the ship's doctor and suffers the effects of strychnine poisoning. The doctor arrives in time to save her life, foiling Cam's fatal plan for now. Cam is overwhelmed with guilt for having suspected Lynne and for his earlier decision to consider murder.

A court later sentences Lynne to life in prison for Polly's murder and her husband's death, closing the immediate case and confirming her guilt in the eyes of the law. Cam's earlier suspicions are vindicated, though the outcome brings no joy in Polly's unresolved illness.

Cam wrestles with guilt and relief that he did not actually kill Lynne, and that Polly's death remains unexplained. He resolves to protect his nephew and live with the consequences of his actions aboard the voyage, recognizing the thin line between love and crime.