Mistresses 4×06 “What Happens In Vegas” – Alec makes a surprise visit and turns Karen’s life upside down when he reveals something new in his life. April and Marc butt heads when it comes to parenting Lucy, putting a strain on their relationship. Kate discovers her new love interest has close ties to Joss and Harry. Joss and Harry get invited to Las Vegas by Harry’s new business partner, Jonathan, and Joss snaps unexpectedly just before they are to be married. Based on the hit UK television series of the same name, “Mistresses” airs Monday, July 11th on ABC.