The Sinner Season 4 Plot
Still reeling from the trauma of a previous case a year ago, the now-retired Harry Ambrose travels to Hanover Island in northern Maine for a recuperative getaway with his partner Sonya, but when an unexpected tragedy occurs involving Percy Muldoon, the daughter of a prominent island family, Ambrose is recruited to help the investigation, only to be thrown into a mystery of mounting paranoia that will turn this sleepy tourist island, and Ambrose’s life, upside down.
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Prices last updated September 24, 2026. Pricing and availability may vary by region.
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Season 4 Episodes
8 episodes
1
68
Part I
Ambrose visits the town of Clark Harbor for a getaway and finds himself at the center of a tragedy.
2
75
Part II
A new suspect leads the investigation into an ongoing feud between the Lams and the Muldoons.
3
74
Part III
Ambrose heads to the mainland to learn more about Percy's past and uncovers dark family secrets.
4
75
Part IV
When the Muldoons push to close the investigation, Ambrose refuses, pushing Sonya to the brink.
5
78
Part V
Ambrose discovers the source of Percy's ritualistic practices and dives deeper into her past.
6
79
Part VI
A shocking new crime further rattles the town of Clark Harbor; Ambrose and Meg team together.
7
79
Part VII
Unsure whom to trust, Ambrose hunts down his pursuers.
8
77
Part VIII
Ambrose exposes the secret that threw Percy's life off course, setting off widespread consequences.