1. Part I
An unassuming housewife stabs a beachgoer to death, which sparks an investigation and creates confusion in a small town.
The Sinner — Season 1
A young mother, overcome by an inexplicable fit of rage, commits a startling act of violence and to her horror has no idea why. An investigator finds himself obsessed with uncovering the woman's buried motive. Together they travel a harrowing journey into the depths of her psyche and the violent secrets hidden in her past.
2. Part II
Cora tries to block Ambrose's continuing investigation, while Mason struggles to come to terms with secrets from Cora's past.
3. Part III
Ambrose unearths a startling secret about Cora that changes the course of the investigation; Mason takes matters into his own hands.
4. Part IV
With Ambrose's help, Cora struggles to recover missing memories, which lead Ambrose to a new suspect.
5. Part V
After a body is discovered in the woods, the investigation into Cora's past deepens.
6. Part VI
When Ambrose begins to waver, Cora convinces him to take a risk for the case.
7. Part VII
Cora finally remembers the night in question.
8. Part VIII
Cora's fate is determined.