Mike thinks Susan is having an affair with Carlos; Bree thinks she is secretly being investigated by her boyfriend; Lynette's sister, Lydia (Sarah Paulson), visits to share some news.
Addison's brother, Archer, moves to Los Angeles to work at Pacific Wellcare; Cooper encourages Violet to discuss her pregnancy with Pete and Sheldon.
Christa must ignore her personal feelings as she and Grace treat a patient who says he was abused at a camp for troubled teenagers; Campbell surprises Grace by asking her out on a date.