Dramatisations of three different women, three different cases—Constance Kent (episodes 1–8), Mary Blandy (9–14), and Adelaide Bartlett (15–22)—all 18th- and 19th-century murderesses.
29 June 1860; Chief Inspector Jonathan Whicher is called to look into the murder of three-year-old Francis Saville Kent, at a large countryhouse in Rode in the County of Wiltshire. The body is discovered in a privy-house.
Three years before the murder, Constance returns from school and argues with her stepmother. She cuts her hair short before fleeing with her younger brother. Her father banishes her for two years but during that period, her brother dies.
Samuel Kent rides to Trowbridge to get the police when baby Francis is missing, believed carried off in a blanket. He offers £10 reward for anyone who finds the child. A maid finds the murdered infant in an out building.
Mr Kent believes the murderer is someone from the village and refuses to allow police to search his home. When a nightdress is found, the Superintendant sets a trap but Kent locks the officers in the kitchen and it vanishes.
Kent tries to deflect blame for the missing nightdress onto servant Mrs Dalimore. Nursemaid Elizabeth Gough is arrested but soon released on the word of Mrs Kent. CI Whicher arrives from London to begin his inquiries.
Constance is arrested for the murder of her brother after it is found that the missing bloodstained nightdress was hers. At Magistrate court, she is released on bond and Witcher's reputation attacked.
Home Secretary brings in solicitor Mr Slack of Bath to make a private inquiry into the Kent murder. Elizabeth Gough is rearrested and released. Samuel has to account for his actions on the night of the murder.
Constance is packed off to France where she took holy orders. During holy week, she tells Miss Greame that she'd murdered baby Francis with a razorblade. She pleads guilty at trial and sentenced to hang but is later commuted.
Summer 1776: Mary Blandy attends a summer ball in Henley, part of recruitment drive for a campaign in Flanders. It's here she meets Captain of Marines, William Cranstoun, who asks to marry her but has no other income.
Mary is shocked to discover Cranstoun is married but he maintains it is not legal. When Cranstoun pays for her mother's illness, he wins favour but when she dies, he remains in Scotland with his assets frozen by his 'wife'.
Cranstoun moves into Mary's home but her father once again refuses to allow them wed without Craunstoun's first 'marriage' annulled, which takes six months. Cranstoun starts to put the idea in Mary's head that her father should die.
Cranstoun returns to Scotland following accounts of his mother's declining health. Mary's father insists that he not return without a letter saying his 'marriage' is void. Cranstoun sends a tonic for her father's health.
As Blandy's health deteriorates, Dr Addington is called from Lincoln and convinced that he's been poisoned. Blandy points the finger at Mary who used a 'love' powder sent by Cranstoun.
Mary pleads not guilty when she's put on trial for the murder of her father Francis. She maintains that the powder she gave her father was a 'love' potion to win favour. Cranstoun flees to France, leaving Mary to the fullest extent of the…
New Year's Eve 1885: Thomas Edwin Bartlett is found dead. Ten years earlier, Frenchwoman Adelaide Comte de Thouars d'Escury meets Thomas while lodging with his brother Charles, in Kingston. They wed in 1881.
In 1882, Adelaide is set to give birth to her first child. However, the labour doesn't go well and the baby dies. Adelaide and Edwin begin a friendship with Reverend George Dyson but her relationship with him goes deeper.
In September 1885, Dyson joins the Bartletts on holiday in Dover. Thomas visits Dyson and asks him to continue visiting his wife. A romance becomes possibility when she tells him her husband has only a year to live.
Thomas has taken to his bed with an unknown illness. Adelaide refuses any help, or visitors, except for Dr Leach. His father demands a second opinion but Dr Dudley can only confirm Leach's opinion.
In late December 1885, Dyson admits he regularly bought chloroform for Adelaide. Thomas is released from hospital and Dr Leach recommends a holiday in Torquay. His father insists he have a nurse but Adelaide refuses.
Despite Thomas looking to the future, he is found dead. Adelaide is allowed to leave and Dyson wants to know what happened to the Chloroform he brought earlier that night. She denies involvement, claiming her husband was a dying man.
At the Coroner's Court, it is claimed chloroform was kept in the bedroom. The jury's verdict puts Adelaide and Dyson in the dock for murder. Prosecution offers no evidence against Dyson and he goes free, leaving Adelaide alone.
Adelaide is tried for Thomas' murder, using liquid chloroform. The jury finds her not guilty, feeling that the prosecution had not showed exactly how the poison was administered.