So this one time? At S.H.I.E.L.D. camp? A bunch of kids sneaked into the pool to blow off steam and it froze over. This wasn't due to irony, though; instead, it turns out a device was planted in the pool's filter days before; also, the device used technology "Leopold" Fitz and Simmons invented, so our heroes are all called in to S.H.I.E.L.D. Science And Technology Academy for the investigation. Or, I should say, our heroes minus May and Coulson, who have other business to attend to. An "Agent Weaver" tells the foursome she's worried a "bad seed" is to blame, and one of the kids who was there thinks this super genius might be responsible – until said smarty spontaneously freezes almost to death in a lecture hall during a Fitz/Simmons speech. Fitz/Simmons, with an assist from Skye, manage to save him, and we quickly learn that Ian Quinn, he of the Gravitanium device, is behind the whole thing in one way or another.
Coulson is still obsessed with the fact that he was like totally dead, and once he's dropped off everyone but May, he tells May he can't wrap his head around what he learned last time, which Fury has since avowed. May, however, thinks he needs to take his mind off it and knows just the thing – the investigation into Skye's past she's been working on. Turns out while the agent who dropped Skye off at the orphanage was killed, her male partner wasn't – he disappeared for twenty-three years, but has just resurfaced in Mexico City, so that's where they're going. While they wait, May tells Coulson that she knows him, and whatever S.H.I.E.L.D. did to alter his memories, she doesn't think they did anything else. In the spirit of honesty, May also confesses about her intimacy with Ward. May and Coulson then catch the agent, who tells them "Avery," the agent who died, and he rescued Skye as part of a mission – because she was an 0-8-4. After they rescued her, people around them started dying, and Avery gave her life to protect her. He warns them to shut themselves from Skye if they want to survive, not that they'll listen, of course.
Fitz talks to the genius kid "Donnie" and tells him he was like him before giving him an idea to solve a tech power problem he's working on – only to soon figure out, with Simmons' help, that the genius kid and one of the others, "Seth", staged the freezing attacks to lure Fitz/Simmons there to solve their power problem. Coulson and May return and Fitz/Simmons brief them on the newly powered ice machine they're now facing; Fitz also realizes that due to how expensive it must have been to make, the students must have a backer, and Skye's investigation quickly figures out it's Quinn.
Seth and Donnie decide to put on the ultimate demonstration for Quinn and create an ice super-storm; later, the S.H.I.E.L.D. plane comes through the storm to rescue Donnie and Seth. Seth suffers a shock from the device and Fitz/Simmons try to save his life, but he dies, and an embittered Donnie gets taken to the Sandbox. Also, he's now like Iceman?
Wrap-up: Coulson comes clean to Skye about his Mexico City investigation, and she cries but bright-sides that S.H.I.E.L.D. has been protecting her for years; Coulson is like whatever w/r/t May and Ward as long as May thinks she can handle it; Coulson calls Quinn, who's all: "The Clairvoyant told me to say hello." DUN DUN DUN!
I'm not sure this is the best-written hour of the series to date, but I think it might be the most enjoyable. I kind of wish they'd started a bunch of these threads in the pilot, but if this is what we can expect going forward I'll be so much happier. So:
At an indoor pool (the fact that the surrounding lights are off suggests they're not supposed to be here), some early-college-age-looking kids talking about advanced science-y stuff. One boy sits antisocially off to the side, but two of the others strip down to skivvies and jump in before calling to the laughing "Callie" to come on in. As the sullen kid packs up his bag and starts to leave, Callie begins to disrobe as well – but in the far corner of the pool, the water starts turning to ice. As it moves toward the kids therein, Callie's smile fades and she tells them to get out, but they're a little slow to realize the danger, and the upshot is that the male one of the two gets half his leg frozen in the ice. The taciturn kid rushes back and uses a skimming net to chip him out (not sure that cheap piece of plastic should have made a dent, but maybe it wasn't solidly frozen), after which the kid, who's sporting shoulder-length hair, stares at the taciturn kid looking terrified but also kind of baleful. The girls then wrap him up in a hoodie – which we see has the S.H.I.E.L.D. logo on it. As Skye would say, we're at S.H.I.E.L.D.-warts!
On the plane, a rear shot of Coulson sitting in his chair suggests pensiveness, which given the revelations of last time is understandable. As we pan in, we see he's in possession of a bunch of photographs of him looking very dead. As he continues to look lost and forlorn, Simmons' voice cuts in on VO that there's nothing more unsettling than being part of something so horrible, but although her comments could obviously apply to Coulson, which is the intention, she's actually talking to Skye, Ward, and Fitz and referring to the incident at the Academy. Fitz tells her they couldn't have known their concepts "would be applied in that way" and Skye references a device found in the pool, so apparently whoever was behind the incident used some scientific theories Fitz and Simmons came up with to implement it. Ward, with a photo of the device (it's a cylinder about a foot long with a control panel on the side), says it was apparently planted in the pool's filter a few days before, so it's logical to assume that whoever activated it was waiting for those specific cadets to be present.