(from CBS's press release, February 2015) UNDER THE DOME returns for its third season with a special two-hour premiere on its new night, Thursday, June 25 (9:00-11:00 PM, ET/PT). It moves to its regular time period on Thursday, July 2 (10:00-11:00 PM), following BIG BROTHER, forming a strong two-hour block of established summer hit shows. Based on Stephen King's bestselling novel, UNDER THE DOME tells the story of a small town that is suddenly and inexplicably sealed off from the rest of the world by an enormous transparent dome. This season, Emmy Award winner Marg Helgenberger will guest star in an extended story arc, beginning with the premiere episode, as the town's inhabitants figure out the Dome's purpose and what it wants from them. UNDER THE DOME was last summer's most-watched (11.32m) and highest-rated scripted program in adults 18-49 (2.8/09) and adults 25-54 (3.7/10).