Color Grimes mystified! Because Team Castlemore is such a strong team of spies who are not actually spies and fuck everything up and constantly get kidnapped! And hug all the time! "The team is DOA without the Intersect working, so why protect something that's going up in smoke? You want to waste time with these idiots, you're on your own." I honestly found everything Casey does and says in this episode to be so self-evident that I didn't even realize it was the C plot until like the last scene when he explains it, but we can just get that out of the way:
Casey's worried about getting called back to Afghanistan or Iraq in the near future, so he's using this Intersect break to psychologically distance himself from the Buy More, and the core four especially, in order to cope with the future stress of leaving. Which: Okay, that's pretty good. I would have cared more if it were Morgan in "danger" and not Jeffster, because that would have involved actual suspense rather than just crossing my fingers, but you need Morgan to be John's cheerleader for the Castlemore family for this story to work at all, so I get it. Basically, what I'm trying to say is that Jeffster ruins everything. They give babies colic and they give Lindsay cocaine and they give your grandma the burps.
Headed into the vault, where Riggle Vulcan-pinches the guards and then sarcastics Chuck into thinking he learned the move from Star Trek when actually it was this particular nonsensical word salad: "Bangladesh meditative trancing; the secret is mind over matter." Thanks for the way better explanation, babe. Once inside, the doors lock and there are "security measures" that involve the temperature dropping while Chuck tries again and again to flash. No luck. He almost immediately pulls out his cell phone and calls Sarah, like he hasn't been watching the episode at all, but there's no signal, so then they freeze to death and die.
Just kidding, Riggle totally knows everything about this vault that was about to kill them, because he did his research, because he is a spy. Also, he opens the vault but instead of one diamond, about six identical ones come popping out of the wall. Chuck takes the opportunity to show off a little spy experience of his own: "Well, they can't just be diamonds. On all my missions, it's never just been diamonds," he says, and then whips out not just a jeweler's loupe but the fact that he took an online gemology class during their flight to Switzerland. Okay, that's kind of hot. Even Riggle's impressed. So they are fakes, made of glass, with a "microdot" of very tiny information inside.