Jean Nicholson and her husband, Frank, are celebrating their fifth wedding anniversary with an elegant soirée at their Southern California home. Jean performs Cole Porter's "I've Got You Under My Skin," delighting their guests. However, the festivities take a dark turn when Jean receives a phone call from Charlie Prescott, an unsavory acquaintance recently released from prison. Charlie threatens to expose Jean's past unless she pays him hush money.

Randy, a private pilot, becomes entangled in a nefarious scheme when Marian, a woman he knows, seeks his assistance. Marian's wealthy husband is found dead, and suspicion quickly falls on her. She claims innocence and persuades Randy to help her prove it.

Laura Starling Morton stands trial for the alleged bathtub electrocution of her wealthy husband. Despite the assistant district attorney's efforts to convict her, she is found not guilty. Unbeknownst to the court, the prosecutor had attempted to strike a deal with Laura: he would sabotage the trial in exchange for half of her $100,000 inheritance—a proposition she accepts.

Henry Wilson is a diligent but unremarkable employee who becomes increasingly agitated when his work is scrutinized by his supervisor, Charles Dodds. Feeling undermined and disrespected, Henry's simmering resentment culminates in a calculated act of murder.

Frankie Cane, portrayed by Dane Clark, is a petty thief who, during an armed robbery, inadvertently kills a store clerk. The next day, he is shocked to see a newspaper photo of the victim—who bears an uncanny resemblance to himself. This eerie similarity unsettles Frankie, prompting him to send his wife away for safety while he lays low.

Eric and Stan, both still grieving the recent death of a woman they each loved, embark on a hunting trip into a remote forest. As they navigate the isolation of the woods, underlying tensions surface. Eric, an avid reader of murder mysteries, begins to exhibit unsettling behavior, leading Stan to suspect that Eric may be plotting to kill him.

Newlyweds Ed and Janet Bliss experience a heated argument, prompting Janet to leave their home in anger. Ed assumes she'll return after cooling off at her mother's place. However, when he contacts his mother-in-law, he's shocked to learn that Janet never arrived. As Ed embarks on a desperate search for his missing wife, he encounters a series of obstacles and red herrings.

The story centers on a meek and unassuming accountant, portrayed by Hume Cronyn, who becomes enamored with a young woman in his office. His growing obsession with her, coupled with his dissatisfaction in his marriage to a nagging and ill wife, drives him to contemplate murder. He plans to poison his wife, believing that eliminating her will free him to pursue his desires.

Alma and Martin Horrell perform a mentalist act, captivating audiences with their seemingly telepathic connection. However, their personal relationship is strained, and Alma desires a divorce. Martin refuses, suggesting instead that a temporary separation might ease their tensions. He departs for Australia, leaving Alma behind.

Dr. Bronson, a psychiatrist, becomes obsessed with understanding the moral constraints that prevent individuals from committing murder. He hypothesizes that five primary factors deter people from killing.