A sleepover between Serena and Dan sets the episode in motion.

Only a kiss is exchanged but the encounter between the former lovers is enough to upend everyone’s world.

Little J continues to be a little schemer, snapping a pic of S and Dan and blasting it via Gossip Girl.

Is there fallout? You know this.

Nate is upset. Dan questions his relationship with Vanessa and re-examines his feelings for Serena.

Dan tells Rufus that Jenny is out of control, meanwhile, and dad's response is to send her packing to Hudson and her mom.

Crestfallen, Little J turns to Chuck, who thinks he’s been jilted by Blair once again after B failed to show at a rendezvous atop the Empire State Building - she came just minutes too late after Dorota gave birth.

Chuck sleeps with Jenny, only to be interrupted by Blair. He tries to salvage the mess he created and is about to propose to her, but ...

At the hospital Dan finds out Chuck took his sis’ virginity. Dan punches Chuck and demands he confess to what happened.

The fact that Chuck slept with J is too much, even for B. She basically tells Chuck it’s over.

She and Serena head off to Paris to begin next season. Jenny heads off to Hudson. Nate drowns his sorrows in a threesome.

Chuck is shot wandering the streets of Prague, his engagement ring for Blair stolen by random thugs.

Dan checks out flights online, only to be interrupted by Georgina. I have a surprise for you, she says, turning to reveal a very pregnant belly.