NBC’s new series “The Event” follows Sean Walker, played by Jason Ritter (“The Class”), as he investigates his fiancée’s disappearance. When Leila, played by Sarah Roemer (“Disturbia”) goes missing, Walker stops at nothing to find her, eventually uncovering the biggest conspiracy in U.S. history. Walker’s mission will affect the lives of a diverse group of strangers, including U.S. President Martinez, played by Golden Globe nominee Blair Underwood (“In Treatment”) and Sean’s father-in-law played by Scott Patterson (“Gilmore Girls”).