Nonton The Sinner: Season 4. 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.