Jo, Zane, and Hendrix make their way to the bunker site armed with anti-instantanium stuff. Jo has also come armed with a bad mood. She says she thinks Carter is in the ventilation shaft, which is the weakest point of the bunker. Zane says she might know that, but how will Carter? Jo says they both looked at the blueprints, and since they work well together and trust each other, unlike some other recently failed pairings, he'll know what she knows. And just in case you're wondering why we've never heard of this ventilation shaft before, Jo and Zane quickly exposit that it was here the whole time but the maps called it a capped well. Even Eva, who was THERE AT THE TIME, had no idea this place existed, or else she surely would have used that as her access point to the bunker instead of bothering with cryptex locks and the like. Whatever. The top of the shaft is easily removed by attaching it to the back of Jo's car and dragging it off.
Eva asks Carter why they're hanging around in the air shaft room. He says it's their "best bet" to be saved. But Eva's gone all negative again, saying no one on the surface even knows they're down there, let alone how to get them out. Carter says he and Jo looked at the same blueprints and would therefore come to the same conclusion. The air shaft is the bunker's weakest spot. She'll look for him here. Eva says the foam is invulnerable. Carter thanks her for reminding him of the direness of their situation. And then, there's a noise. Yes, Jo and Zane have CGI-exploded the instantanium away, freeing Carter and Eva. Jo lives it up in her moment of glory: "my name is Jo Lupo and I'll be saving your ass today!" she says. "Somehow, I'll promote you," Carter says, looking like he could kiss her. Jo doesn't seem to be holding out much hope of that, but that's only because she doesn't know what foreshadowing is.
Then Carter's back at Zoe's bedside. With Lexi. Ugh. Zoe is sleeping, because that's what old people do. How come she doesn't look any older? Shouldn't she have a healthy dose of Star Trek age advancing make-up on at this point? Allison walks in and tells Carter that Eva is now assisting Henry in finding a cure. Allison says it's especially important that they find one, since the Element X did, in fact, make it into the groundwater. Then ... shouldn't they be running around town right now telling people not to drink the water or take showers? Lexi tries to be a good guest and sister by saying "you guys are lucky you don't have a boss. Otherwise, he'd come down here, he'd kick your -- " and she's interrupted by Allison getting a phone call. Hey, is it possible that they can cure everyone in town except Lexi? Please?