This week on "Gossip Girl," Serena (Blake Lively), Blair (Leighton Meester), Nate (Chace Crawford), Chuck (Ed Westwick) and their entourage break into the school swimming pool for a night of fun. But when a member of their group nearly drowns, the school threatens to expel the person responsible for the break-in.

Everyone agrees to keep a secret pact and say nothing, but it ultimately creates major tension between Serena and Dan (Penn Badgley), who isn’t sure he’s ready to take the fall for someone else and risk his future.

Vanessa (Jessica Szohr) is working on a documentary project about private schools and accidentally captures Blair and Chuck discussing their affair.

Lily (Kelly Rutherford) contemplates telling Rufus (Matthew Settle) how she really feels about him. Taylor Momsen also stars.

"Gossip Girl" airs at 9 p.m. ET on the CW.

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