Jill says it's not a bomb, it's a clue, because Gui wanted to help people, not hurt them. Sarah thinks she's wrong and it's too dangerous, but Jill says smugly that she's never wrong. They try to solve the puzzle, which is a sheet of music, as Casey evacuates the building. They solve the puzzle, with the bad Fulcrum guy looking on. Chuck's excited, and he and Jill kiss. Sarah can't stand it and turns the other way. Casey says he loves love, and Sarah looks at him and rolls her eyes. I like that Casey speaks up about all of this, and knows exactly where Sarah stands with Chuck, feelings-wise. He might not care about feelings, but he sure does know about them.
Back at OOSSL, Agent Redhead says the computer is trying to find an encryption key to figure out the data. She wants them to thank Chuck for his service, and wonders where he is. Casey guesses he'd be rounding second base. Sarah looks upset. Back at Chuck's, Jill and Chuck are getting hot and heavy on his bed, when he stops it, because he can't do it in front of the camera. He tells her to meet him at the Buy More tomorrow. She asks what time, and he says (I have to quote this directly): "Take the latent heat of aquatic fusion ... and subtract the atomic number of thulium." He asks if she's got it, and she does. We get a shot of Casey listening in. He says, "Nerd code," and appears to be stumped. But, um, the meeting is tomorrow, Casey. Look those things up. You have infinite resources at your disposal, I'd think. Or you can just start with Google.
The next day at the Buy More, Chuck asks Morgan to cover for him with Buster. Morgan asks if it's a big night with the lady, and Chuck says it is. Morgan asks something about Sarah, and Chuck starts to agree, when Morgan tells him to save it because he knows about Jill. Morgan says they're best friends and if he's keeping this a secret, what else doesn't he know. Chuck apologizes and says there are a lot of things he wants to tell him, but can't. Morgan says Chuck's never lied to him, and Chuck tells him to trust him. Chuck has to leave, so asks if Morgan will cover for him. Morgan will, but he moralizes a bit first, saying friends lie for each other, not to each other.