Originally Aired: July 16, 1957

A Case For Doctor Morelle #13, "Mr X," a mysterious patient with no memory or identification lies recovering in a hospital, while author Paula Maitland finds herself tormented by persistent anonymous telephone calls. The caller's voice, strange and unsettling, repeatedly asks about her overdue second novel, driving the successful writer to distraction and preventing her from working. Inspector Hood refers her to the brilliant Dr. Morelle, who agrees to visit her home that evening to hear the mysterious caller for himself. Miss Frayle, ever eager to help, insists on accompanying the doctor in case danger arises.

However, before Dr. Morelle can investigate, Paula's husband arrives with a shocking allegation: he believes his wife never actually wrote her bestselling first novel, Broken Journey. He claims she returned from a holiday in Devon with the completed manuscript, but her inability to produce a second book reveals her as a fraud. As Dr. Morelle prepares to untangle this web of mystery, the connection between the amnesiac Mr. X and Paula Maitland's literary deception begins to emerge.

Originally Aired: July 9, 1957

A Case For Doctor Morelle #12, "Poisoned Air," Doctor Morelle and his secretary Miss Frayle are invited by Professor Hugo Russell to witness a demonstration of his new poisonous gas, designed to kill insect pests. The professor also mentions his upcoming wedding to his secretary, Miss Bella Goodwin, though his legendary absent-mindedness raises questions about whether he'll even remember to attend his own ceremony. When they arrive at the laboratory the next morning, tension crackles beneath the surface. The professor's assistant, the handsome Kurt Emmanuel from Vienna, harbors deep feelings for Bella and attempts to convince her to call off the wedding. Meanwhile, the dangerous gas they've been developing proves as lethal as promised, capable of causing sudden death with just a whiff. As romantic entanglements collide with deadly scientific work, Doctor Morelle finds himself drawn into a case where poisoned emotions may prove just as dangerous as poisoned air.

Originally Aired: July 2, 1957

In A Case For Doctor Morelle #11, "The Gambler," the famous detective and his secretary Miss Frayle are drawn into a puzzling case when they stumble upon a ringing telephone box during an evening walk. Answering the call, they hear the frantic voice of Mrs. Ludlow summoning a doctor to her Chelsea home, convinced something terrible has happened to her husband Alex. The distressed woman explains she returned early from a party, gripped by a premonition of disaster, but was too frightened to enter her husband's study herself. When Dr. Morelle and Miss Frayle investigate, they find the room empty, despite Mrs. Ludlow's certainty that her husband was inside.

As the episode unfolds, hints emerge about Mrs. Ludlow's dangerous gambling obsession, particularly her reckless behavior at the roulette table where she loses considerable sums. Dr. Morelle observes that she exemplifies the gambler's fallacy, refusing to accept that each spin of the wheel is independent of the last. The case promises to spiral into what Dr. Morelle describes as a vortex of disaster and death, with Mrs. Ludlow's compulsion at its center.

Originally Aired: June 25, 1957

A Case For Doctor Morelle #10, "The Wedding Dress," young Audrey Templeton is plagued by mysterious nightmares and unexplained disturbances in the days leading up to her wedding. Her aunt, Mrs. Lambert, seeks Doctor Morelle's help after someone repeatedly enters Audrey's bedroom at night, and the frightened bride-to-be becomes convinced that someone is trying to prevent her marriage to Johnny Fitzgerald. Mrs. Lambert reveals that Audrey was engaged once before three years ago, but her fiancé Richard Conway vanished during a mountain climbing expedition and was never found.

While Mrs. Lambert consults with Doctor Morelle in London, a terrifying incident occurs at home. Audrey narrowly escapes being crushed against a garage wall by the family car when the chauffeur Ames fails to notice her presence. Is this another accident, or is someone deliberately trying to harm the nervous bride? Doctor Morelle agrees to visit the Lambert household that evening under the pretense of being interested in haunted houses, hoping to determine whether Audrey's fears are merely pre-wedding anxiety or something far more sinister.

Originally Aired: June 18, 1957

A Case For Doctor Morelle #9, "The Black Ruby," Mr. Hampton seeks Dr. Morelle's help after surviving a harrowing plane crash over the Indian Ocean. Hampton recently purchased a legendary Burmese ruby known as the Black Ruby in Bombay, despite warnings from the jeweler who authenticated it. Now safely back in London, Hampton faces a new crisis: his wife Sonia is convinced the cursed gem will bring disaster to their household and desperately wants him to dispose of it. Hampton fears his neurotic wife may do something drastic if he refuses.

Dr. Morelle suspects Sonia's anxiety stems from deeper marital problems rather than superstition, particularly Hampton's frequent travels without her in pursuit of precious stones. When the doctor and Miss Frayle accept an invitation to dinner at the Hampton residence to meet Sonia and view the infamous ruby, a chandelier suddenly crashes from the ceiling, nearly killing the couple. Sonia becomes even more convinced the Black Ruby's deadly reputation is real, while mysterious admirers and questionable friends complicate the household tensions surrounding the cursed gem.

Originally Aired: June 11, 1957

In A Case For Doctor Morelle #8, "Act Of Violence," Doctor Morelle and his secretary Miss Frayle travel to the Essex countryside to visit Professor Stenberg. On their way, they stop at a garage for directions and encounter a young man who seems strangely disturbed by the doctor's presence. Miss Frayle notices the man's reaction when he hears Doctor Morelle's name, and the doctor cryptically mentions recognizing him from a previous "sordid, lurid affair." The man is Robert Benson, whose name appears on a poster advertising a local concert performance.

When they arrive at Professor Stenberg's house, the peaceful visit is disrupted when Benson appears in the garden beneath Miss Frayle's balcony. He desperately insists on speaking with Doctor Morelle, warning Miss Frayle that it's for the doctor's own good. Benson is agitated and defensive, believing the doctor has deliberately come to the area to investigate him. The young man was previously convicted of murder at the Old Bailey, a trial Doctor Morelle attended, though he insists he's innocent. As tensions mount, Doctor Morelle agrees to meet with the clearly troubled young man to discover what he wants.

Originally Aired: June 4, 1957

A Case For Doctor Morelle #7, "The Will," Dr. Morelle receives an urgent call from David Beaumont, who is suffering from a severe asthma attack triggered by roses on his breakfast table. When Beaumont arrives for treatment, the doctor employs an unusual technique involving paper roses and a fake adrenaline injection to demonstrate that his patient's condition is psychological rather than physical. Through careful questioning, Dr. Morelle uncovers the truth: Beaumont's asthma attacks began after he discovered his wealthy Uncle Herbert unconscious in the bathtub and briefly considered leaving him there to die in order to inherit under his will.

Beaumont confesses that his uncle constantly changes his will, sometimes leaving everything to him, sometimes to his eccentric Aunt Henrietta, and sometimes to Darrell the manservant. Broke and unemployed, Beaumont has been making calculated visits to his uncle's strange household near Wimbledon Common, hoping to stay in the old man's good graces. Dr. Morelle diagnoses the young man's asthma as stemming from profound guilt over his mercenary motives, and prescribes that Beaumont focus on finding employment to make himself independent of any inheritance.

Originally Aired: May 28, 1957

In A Case For Doctor Morelle #6, "Voice In The Night," an elderly woman named Miss Nicholson arrives at Dr. Morelle's office with a disturbing tale. For the past week, she has been receiving mysterious midnight phone calls from a man warning her that someone is after her money and plans to murder her. Despite reporting the threats to the police, they dismiss her concerns as the worries of a nervous spinster. Living alone in a small Chelsea house with only her elderly dog Billy for company, Miss Nicholson turns to Dr. Morelle for help based on a friend's recommendation. She insists she has no money worth stealing, yet the anonymous caller seems convinced otherwise.

After listening to her story, Dr. Morelle agrees to investigate and reassures Miss Nicholson that the threats may not be serious, since warning a victim seems counterproductive for a genuine criminal. However, when Miss Nicholson accidentally leaves her shabby handbag behind, Miss Frayle discovers it is stuffed with five pound notes, possibly thousands of pounds worth. When Miss Frayle rushes after her to return it, Miss Nicholson has mysteriously vanished from Harley Street without a trace.

Originally Aired: May 21, 1957

A Case For Doctor Morelle #5, "The Blackmailer," Sir Clifford and Lady Forbes desperately seek Doctor Morelle's help when their daughter Cynthia attempts suicide twice by gas and refuses to explain why. The young woman recently returned from London, where she was supposedly in the company of Count Raymond Alvaro, a distinguished older Spaniard to whom she became attached during a family vacation in Spain. Doctor Morelle discovers that Cynthia cashed a cheque for two hundred and fifty pounds at her London bank before returning home, and the money has since vanished without a trace.

Working with Inspector Hood, Doctor Morelle investigates Cynthia's movements in London, interviewing staff at Christie's Hotel where she stayed. The trail leads to a darker truth about the charming Count Alvaro and his associate Harry Fox. Doctor Morelle deduces that Cynthia has fallen victim to a sophisticated blackmail scheme involving compromising photographs, preying on her youthful inexperience and fear of scandal. As the investigation unfolds, the detective must not only apprehend the criminals but also help the Forbes family navigate the delicate aftermath of their daughter's traumatic experience.

Originally Aired: May 14, 1957

In A Case For Doctor Morelle #4, "The Sleepwalker," the brilliant but acerbic Dr. Morelle investigates a disturbing case involving Richard Wilson, a young man plagued by terrifying nightmares in which he attempts to murder his mother with a stiletto. When Richard's mother is found dead in circumstances suggesting a burglary gone wrong, the troubled sleepwalker becomes the prime suspect. Complicating matters is Richard's secret romance with Helen Keene, his mother's secretary companion, a relationship his domineering mother would never have approved. Inspector Hood believes a burglar killed Mrs. Wilson when she interrupted a robbery, pointing to evidence of forced entry and a torn necktie clutched in the victim's hand.

However, Dr. Morelle's keen psychiatric insights and careful examination of the crime scene reveal inconsistencies that don't align with the inspector's theory. As he questions Richard, Miss Keene, and examines the physical evidence, Morelle uncovers a far more sinister plot involving insurance policies, suicide clauses, and the psychological principle that criminals are driven by an inner compulsion toward self-destruction. The doctor's investigation leads to a shocking revelation about who orchestrated this elaborate scheme and why.