Sparkling Cyanide

The novel opens with six people reflecting on the death of Rosemary Barton, a beautiful young woman who apparently committed suicide by cyanide poisoning at her birthday dinner in a London restaurant called the Luxembourg nearly a year earlier. Each narrator reveals a different relationship to Rosemary and a different possible motive for wanting her dead.

Iris Marle, Rosemary's younger sister, grew up in Rosemary's shadow. Rosemary inherited an enormous fortune from Paul Bennett, their mother's devoted admirer, under terms stipulating that if Rosemary died childless, the estate would pass to Iris. A week before her death, Iris found Rosemary composing what appeared to be a farewell letter; this document later supported the inquest verdict of suicide. Six months afterward, Iris discovered an unsent love letter in Rosemary's dressing gown addressed to someone called "Leopard," revealing Rosemary had a lover and planned to leave her husband, George Barton. Iris suspects the lover was either Stephen Farraday, an ambitious politician, or Anthony Browne, a charming but mysterious man. George has now shown Iris two anonymous letters declaring Rosemary was murdered and insists one of the dinner guests must be the killer.

Ruth Lessing, George's capable secretary, has been silently in love with her employer for years. She resented Rosemary deeply, a feeling sharpened when Victor Drake, Rosemary's disreputable cousin, told Ruth she was the kind of woman who should have married the boss. The encounter awakened Ruth's buried hatred.

Anthony Browne recalls being dazzled by Rosemary but quickly realizing the attraction was shallow. Rosemary discovered his secret: Victor Drake, who had been in prison, recognized Anthony as Tony Morelli, an ex-convict. Anthony threatened Rosemary to keep quiet. He planned to leave London but changed his mind after seeing Iris, struck by her genuine character.

Stephen Farraday built his political career by marrying Lady Alexandra Hayle (Sandra), the shy daughter of the powerful Lord Kidderminster. At St. Moritz, Stephen fell into a reckless affair with Rosemary. When he tried to end it, Rosemary refused and threatened to tell both spouses. Sandra knew about the affair from the start but concealed her anguish behind a proud facade. She hated Rosemary and wished her dead. On the night of the birthday party, she gave Rosemary a headache cachet in the ladies' cloakroom.

George devises a plan: a dinner party at the Luxembourg on November 2nd, All Souls' Day, recreating the original evening with the same guests, an empty seventh chair, and a sprig of rosemary on the table. He believes this will expose the murderer. Colonel Race, a former intelligence officer and long-standing family acquaintance, visits George at Little Priors, the country house George purchased near the Farradays' estate. George shows Race the anonymous letters, and Race identifies Stephen as the most obvious suspect. Race urges George to go to the police, but George insists on springing his own trap.

Stephen and Sandra, sensing the party is a trap, resolve to attend together. In an emotional exchange, Sandra reveals she has always known about the affair, and Stephen confesses he truly loves her. Meanwhile, Anthony asks Iris to marry him secretly and immediately. She refuses, questioning why such secrecy is necessary.

The dinner party proceeds under strained tension. After the cabaret, the guests feel relief that nothing terrible has occurred. George stares at the empty chair, visibly disturbed; his plan has gone wrong. He proposes a toast to Iris's birthday, then a second toast to Rosemary's memory. Everyone drinks. George sways forward, clutching his throat, his face turning purple. He dies within minutes from cyanide poisoning.

Chief Inspector Kemp takes charge of the investigation, and Race explains George's belief that Rosemary was murdered. The most valuable witness is Christine Shannon, a sharp-eyed young woman who had been dining at one of the adjacent tables in the restaurant alcove. She confirms that no one approached the table while the party danced except a busboy who picked up a green and gold evening bag from the floor and replaced it on the table. Kemp interviews the Farradays, where Sandra diplomatically deflects questions about her husband's relationship with Rosemary.

Race questions Ruth over lunch. She provides a crucial detail: Before the original dinner, Sandra gave Rosemary a headache cachet in the cloakroom, opening another possible method of administering poison. When pressed about the night George died, Ruth hesitates before answering "Nothing," and Race senses she is withholding something. Race then tracks down Betty Archdale, a former parlourmaid from the Barton household, who reveals she overheard Anthony threatening Rosemary and knows his real name is Tony Morelli.

Kemp confronts Stephen with evidence of the affair; Stephen admits it but denies involvement in either death. Race confronts Anthony with his identity as Tony Morelli. Anthony reveals he is an undercover intelligence agent who spent three years infiltrating an international sabotage ring. His prison sentence was real, arranged to establish his cover.

Iris confides a terrifying secret to Anthony: After George died, she found a paper packet of cyanide planted inside her handbag. In her shock she dropped it under the table. Anthony insists she report this to Kemp immediately.

Race, Kemp, and Anthony confer. Kemp suspects Sandra; Race suspects Iris herself, citing her motive of inheriting the fortune. Anthony then has a breakthrough. He recalls Christine Shannon's testimony: The busboy placed Iris's dropped bag one seat to the left of her actual position. When Iris and George returned to the table first, Iris sat where her bag was, one place over, and George sat beside her in what he assumed was his seat. George unknowingly drank from Iris's glass, which had been poisoned. Iris, not George, was the intended victim all along.

The implications crystallize: If Iris dies unmarried, her fortune passes to her aunt Lucilla Drake, and effectively to Lucilla's son Victor, who has always extracted money from his mother. All evidence of Victor being in South America depends on Ruth's word alone. George originally sent Ruth to arrange Victor's deportation, and during their encounter, Victor drew Ruth under his influence. She has been his accomplice ever since. Victor left Buenos Aires weeks earlier and attended the Luxembourg dinner disguised as Pedro Morales, a patron at the neighboring table. A former actor and former waiter, Victor posed as a server during the cabaret and poisoned the glass at Iris's place. Ruth planted the cyanide packet in Iris's handbag.

Realizing Iris is in immediate danger, the three men race to the Barton household at Elvaston Square. They find Iris's bedroom door locked, gas pouring from beneath it. Anthony and Race break down the door and find Iris unconscious by the open gas jet. They revive her just in time. Ruth, who had visited on the pretext of discussing funeral arrangements, struck Iris unconscious, arranged the scene to look like suicide, and slipped out. Kemp follows Ruth to a parked car, confirming her premeditation.

In the final scene at Little Priors, Anthony explains the complete solution to a recovering Iris. Victor has been arrested in New York. The anonymous letters were written by Ruth, designed to stir George into staging the dinner party that was supposed to end with Iris's death. Anthony gently touches a sprig of rosemary blooming out of season, saying goodbye to Rosemary's memory. Iris whispers the novel's refrain: "That's for remembrance."