The Sinner Guest cast, played by Peggy Gormley Episode 1x01: Part I (Aug 2, 2017) Episode 1x02: Part II (Aug 9, 2017) Episode 1x03: Part III (Aug 16, 2017) Episode 1x06: Part VI (Sep 6, 2017) Episode 1x08: Part VIII (Sep 20, 2017)