Buy it now.Executive produced by Josh Schwartz ('Chuck,' 'The O.C.') and Stephanie Savage ('The O.C.'), and starring an impressive ensemble of young stars, season three of the fashion-forward series enters all-new territory. Serena (Blake Lively) returns from a summer in Europe with a lot on her plate. Who will she turn to for solace? Jenny (Taylor Momsen) is reigning Queen Bee at school, but will others respect her if she refuses to use her influence for bad? Chuck (Ed Westwick) and Blair (Leighton Meester) had a summer of fun, but will their new relationship survive the fall, especially as Blair prepares for New York University, as do Dan (Penn Badgley) and Vanessa (Jessica Szohr)? And how will Nate (Chace Crawford) fit into things with his new girlfriend, Bree (recurring guest star JoAnna Garcia), on his arm? Other guest stars include Michelle Trachtenberg, Sebastian Stan, Hilary Duff, Chris Riggi, Tyra Banks and a musical performance by Sonic Youth. Kelly Rutherford and Matthew Settle also star.