The culprit? Jenny, who has assimilated into Blair's old clique, for better or worse.
Nate (Chace Crawford) tries to warn Jenny that the clique will turn on her as they did Blair, but little J doesn't heed his warning. Serena tries to tell Blair that she'll bounce back more quickly if she's nice, and so she encourages B to attend J's birthday party.
Serena's got her own set of problems, though. Well, one. Her future step-sibling Chuck (Ed Westwick), is all up in her bathroom and cramping her style. It gets worse when she receives a mysterious package full of porn and handcuffs that she assumes is his doing. He denies it, however.
Blair shows up at the hot club Butter for J's big party, but Jenny and the gang are actually holding the shindig elsewhere. It was a trick to shame the former Queen Bee.
But J runs into her own issues... short on cash to run with this crowd, so she yoinks some stuff out of her friend's closet and trades it in for a wicked nice dress.
Serena receives another mysterious package: three cases of champagne in front of the school. Again, fingers are pointed at Chuck.
Out for revenge, Blair goes to see Rufus (Matthew Settle) to warn him that it'll be tough for his daughter to keep up with these popular girls. She offers to help in any way she can - she's so NICE!
Blair is up to something.
Meanwhile, Jenny's friend notices that a one-of-a-kind Valentino dress is missing from her mom's closet so J freaks and tries to return it - but no dice. The clerk can't accept the return. J panics, calls Nate and asks for $8,000. She hangs up before explaining why, then steals the Valentino back by wearing it under her clothes instead.
Lily (Kelly Rutherford) is worried about these packages Serena is getting and assumes her daughter is acting out. Serena instead blames Chuck.
Across town, Blair has organized a surprise party at Jenny's place. Little J is a bit freaked out when she walks in and sees the entire gang. Jenny desperately tries to change out of the Valentino dress before anyone sees, but gets busted. Realizing that Jenny is a thief, the posses abandons her and follows Blair to Butter.
When Rufus demands to know where she got the dress, Jenny breaks down and whines about how poor they are. While this is going on, Nate tracks down Dan and tells her about Jenny's phone call.
Meanwhile, Serena is distressed by the fact that Eric is hanging out with Chuck - and by another small package that arrives for her with no return address, this time full of of cocaine. Serena freaks.
Serena again blames Chuck, but he's busy getting kicked out of the pad by Bart, who also assumes he's behind this string of bad behavior.
At Butter, Blair waits for the gang to arrive, worried that they're going to ditch her again. This time they show up. Queen B is back.
While Dan and Rufus discuss what to do about Jenny, she escapes, goes to see Nate and asks him to take her to Butter. They sit down at B's table, and the gang, impressed by J's ability to bring Nate (who one of the cronies has a thing for), forgive her for the dress theft.
Looks like the Jenny-Blair rivalry is just beginning.
Serena's next mystery package finally reveals that lo and behold, it's not Chuck tormenting her. It's a letter from "G," who owns up to sending all the goodies, and says she'll be coming back to town.
Serena's past is coming back to haunt her. She apologizes to Chuck, shows him the letter, and he invites her in for a drink.
(Source: TV Fanatic)