NGTV Guide: Monday, September 21

The CW and Fox got a headstart on the fall season, but now that the Emmys have officially put paid on the last television season, we’re going into premiere overload. Tonight the Nice Girls welcome back a devilishly charming author and tune in for the further adventures of Manhattan’s teenage elite.

Gossip Girl – the CW 9/8c
“The Freshmen” – Blair, who is determined to maintain her Queen status in college, embarks on her first day at NYU, along with Dan and Vanessa. Unfortunately, Georgina (guest star Michelle Trachtenberg) turns up as Blair’s roommate in the dorms, determined to make Blair a social outcast. As Serena prepares to depart for Brown, she and Chuck have a major falling out, so she recruits Chuck’s enemy, Carter (guest star Sebastian Stan), to help her get even. Nate and Bree (guest star JoAnna Garcia) decide to explore their relationship further, knowing full well it could cause tension between their families who are political rivals.

Castle – ABC 10/9c – SEASON PREMIERE
“Deep in Death” — When the new season begins, Castle is wrestling with how to repair his relationship with Beckett, while struggling to finish his soon-to-be-published bestseller, Heat Wave. But circumstances force the pair back together to investigate the mysterious murder of a man found dead, tangled in the limbs of a tree.