When Robert Crane is charged with the murder of his sister's estranged husband Perry needs the testimony of sister Helen Reed to clear him of the charge. Unfortunately for all concerned, Helen suffers from multiple personality disorder and the second personality, Joyce Martel, is the one who is needed as the witness. Helen's psychiatrist puts her under hypnosis so Joyce can tell what she knows about the case.

Doris Hocksley is shown a personal newspaper ad in a Los Angeles newspaper for locating the daughter of Adam Hocksley and providing proof of same. A friend, John Lowell, suggests she pursue the idea to prove she is the rightful heir to Adam Hocksley estate. Alan Neil is the nephew of Elston Carr, the executor. He meets Doris Hocksley and suggests they work together, for a price, to convince the executor. Later that evening Elston Carr is found dead in his home by Rebecca Gentrie, the secretary. She locks the door to the room to keep whoever is inside from escaping and calls the police. The police open the door to find Doris Hocksley. She is accused of murder when they find her fingerprints on the murder weapon.

Gossip columnist Mary K. Davis is found murdered and it seems there is no shortage of suspects. There was her politician-husband to whom she refused to grant a divorce. There was her timid secretary whom she bullied. There was the secretary's boyfriend who had some secrets in his past. There was the doctor running an illegal baby-selling scheme whom Mary threatened to expose if he didn't give her a child. Leona Walsh, the doctor's nurse, ends up being charged with the crime and this time Perry has to tamper with some evidence in order to clear his client.

Enid Griffin, the secretary of Stewart Brent, attempts to commit suicide after learning her boss has married. Arthur Binney attempts to blackmail Stewart Brent with facts about his new wife having been in jail for fraud. When Stewart Brent goes to meet Arthur Binney at a motel for the payoff, he is knocked unconscious. He awakens to find Arthur Binney dead in the next room and is put on trial for murder.

While a woman is searching the office of the South African Diamond Company, George Baxter enters to meet Walter Lumis and Duane Jefferson. He notices things in disarray and questions the woman. She makes an escape, enters Perry Mason's office, and pretends to be a typist sent by a temp agency. She leaves unannounced a short time later. Meanwhile Baxter calls for the police assuming a robbery has taken place. That evening the dead body of George Baxter is seen being thrown from a pier. Duane Jefferson is identified as the person who threw the body off the pier and is accused of the murder. However he refuses to identify the woman who could prove his innocence.

Sarah Werner asks Perry to find her husband, Hugo Werner, who ran off with her inheritance. Hugo, now using the name Hans Breel, is now working on a gem scam but his scheme backfires when he is murdered and Sarah is charged with the crime.

A circus clown is charged with the murder of its part owner when a gun is slipped to him during a gun act.