Gossip Girl - Season 1 - Eps 12: School Lies
Serena, Blair, Nate, Chuck and their class break into the school swimming pool for a night of fun, but when someone nearly dies, the school threatens to expel the person responsible for the break-in. Everyone agrees to not say anything, but this creates major problems between Serena and Dan. Vanessa, while working on a documentary project about private schools, accidentally captures Blair and Chuck discussing their affair. Lily tries to tell Rufus how she really feels about him.
About Gossip Girl

Title: Gossip Girl
First Air Date: 2007-09-19
Last Air Date: 2012-12-17
Status: Ended
Rating: 8.202/10 (from 2159 votes)
Language: EN
Seasons: 7
Total Episodes: 121
Network: The CW
Genres: Drama, Mystery
Production Companies: Warner Bros. Television, Alloy Entertainment, Fake Empire Productions, CBS Studios
Synopsis
An exclusive group of privileged teens from a posh prep school on Manhattan's Upper East Side whose lives revolve around the blog of the all-knowing albeit ultra-secretive Gossip Girl.
Cast

Blake Lively
Serena van der Woodsen

Leighton Meester
Blair Waldorf

Penn Badgley
Dan Humphrey

Chace Crawford
Nate Archibald

Ed Westwick
Chuck Bass

Kaylee DeFer
Ivy Dickens

Kelly Rutherford
Lily van der Woodsen

Matthew Settle
Rufus Humphrey