It's time for Chuck and Sarah's engagement party, and Chuck just can't believe Sarah doesn't want all her friends and family invited, so he invites her old friends, the CAT squad. They're essentially Charlie's Angels, complete with narration by a mysterious "Charlie" character and all. It's Carina, Zondra and Amy -- all beautiful and all spies, of course. Chuck invites them, and they show up, but Sarah's less than happy about it. See, she never trusted one of them, Zondra, and they bicker from the moment the three ladies show up sexily at Chuck's apartment to capture Sarah for her bachelorette party or whatever. (Turns out General Redhead also has an assignment for them, thanks to a flash by Chuck: They need to capture Lou Diamond Phillips and his evil accent while down in Brazil for Carnival. Chuck and Casey are there to guard from the van, and Carina's not there because she hurt her leg, leaving her stuck back at Castle with Morgan.)
In Brazil, the ladies (in cute white dresses) are surrounded pretty quickly, courtesy of a call someone made to alert Lou Diamond Phillips they were coming. Lou Diamond ties up the CATs and offers them all a job. He needs skilled operatives, after all, he says, as he calls them "kitties." It's as creepy as it sounds. While Lou Diamond is making his sales pitch, Sarah accuses Zondra of being with him. She denies it, and just as Lou Diamond's about to kill Sarah she breaks free and asks him to tell her the truth. Chuck busts in and rescues her with his Intersect-fu. Problem is, she doesn't get the info. So she cuts Chuck down all brutally, and General Redhead congratulates them on capturing Lou Diamond, then orders the CATs to stay in Castle until Casey can interrogate them and determine who the mole is. They ultimately determine it's Amy, and Sarah ultimately determines she does need friends; she invites both Carina and Zondra to be bridesmaids and then Ellie to be her maid of honor. Oh, and she and Chuck make up.
Morgan and Alex have a minor tiff over the lipstick on his collar (strategically placed there by a flirtatious Carina, jealous that Morgan's no longer pathetic for her). Alex ends up breaking up until Morgan declares his pathetic love (and we're supposed to believe Alex is just as pathetic, which isn't realistic). She declares hers back, and all is right with the world and their love for now.
A wannabe Charlie voice voices over about nothing at all as we get close-ups of pretty girls' eyes, including Sarah's. He says his spy team, the CAT squad, was the best spy team in the business in 2003. They were: Cold-hearted Carina, the bitch Zondra, party girl Amy, and Sarah Walker, his pride and joy. Charlie's Angels-style opening as we see CAT means "Clandestine Attack Team." FauxCharlie: "Go get 'em, Cats!"
At the Buy More, Morgan's in fantasy land (which is apparently what this intro was) because of Chuck telling him about the Cats. Chuck just hopes these girls still love Sarah, because he's running short on friends for Sarah for the party. Morgan suggests the wild notion of asking Sarah. Chuck says she doesn't want to invite anyone, but he knows she'd want people there, so he's nudging. Morgan wonders what this has to do with him, and Chuck says one of the Cats is Carina. Morgan wonders if she really has to be, because that puts two of his lovers (her and Alex) in the same place. Not good. Chuck just wants her contact info, though, and Morgan obliges. (Her email address, by the way is "Carina_azzkickr.")
Soon enough, we see Carina beating the crap out of some guy when she gets a text. It's an invite for all of the Cats to Sarah's engagement party. Carina quickly calls up Amy and asks about Zondra, getting the whole team back together for their old friend, Sarah.
Sarah and Ellie run into each other in the courtyard -- Ellie's on the way to see her in-laws, the Awesomes -- and touch base on wedding stuff, and the engagement party. Sarah says she's concerned because she told Chuck she didn't want to invite anyone, but now he wants to discuss some big idea with her. She doesn't want him digging into her past, which is a bit complicated. They agree that Chuck tends to dive in head-first. Ellie tells Sarah she can always come to her about complicated family situations, wedding stuff, or anything else. Sarah walks into the apartment, notices Chuck has a bunch of glasses and dishes out, so asks if they're having company. Chuck tells her she is, and offers these two words: "Cat squad!" Sarah looks less than pleased, and then she's full-on angry. He thinks these girls could be her bridesmaids or something, but she says she's changed a lot since she saw them last. She wishes Chuck would have talked to her about this beforehand, and she tells him that Carina? She was the mellow one. Chuck gets that she's nervous, but compares this to searching for and finding his mom. Sarah says you don't know what to expect with this team.