ER alumna Maura Tierney is set to star opposite Dominic West and Ruth Wilson in Showtime‘s drama pilot The Affair. From playwright and writer/producer Sarah Treem and co-creator Hagai Levi, The Affair is an intense and intimate exploration of two marriages and an affair that disrupts them — with all of the complex consequences that result. It centers on Noah (West), a good husband, devoted father of four, and New York City high school teacher whose settled, comfortable world is about to implode when he meets a woman (Wilson) he thinks is his soul mate. Emmy-nominated Tierney, repped by UTA and Untitled, will play Helen, Noah’s college sweetheart, best friend, mother of his children, lover and wife of 17 years. Her world will be buffeted by Noah’s infidelity and, over time, she will swing back and forth from understanding to furious, from forgiving to vengeful. Tierney, who recurs on CBS’s The Good Wife, recently made her Broadway debut opposite Tom Hanks in Lucky Guy.