"The Affair" follows two marriages and an affair that disrupts them. The drama will be told from the male and female perspective.
According to TVLine, the "ER" veteran will play Helen, the wife of Dominic West's character Noah in the Showtime drama pilot. Ruth Wilson will also appear in the pilot as Alison, a young married woman who works at a pancake house and is trying to piece her life back together in the wake of a tragedy.
West's character, a father of four, makes Alison question the choices she's made. Tierney's character will see her foundation shaken by Noah's affair, according to TVLine.
Sarah Treem wrote the original script with Hagai Levi. The duo first worked together on "In Treatment."