As the rest of the team watches in trepidation, Fitz uses gloved hands to take a sample of the Chitauri's residual cells from the helmet (although that's not going to help if the helmet decides to zap him) and Simmons then gets to work. After a quick montage, Fitz puts Simmons work into the delivery system and injects the last rat, and nothing happens, which they take to mean they were successful -- but then telltale blue light appears and the third rat floats up to join his brethren. After taking a moment, Simmons puts on a brave smile and walks over to Coulson to ask him to ignore protocol and tell her father first; her voice breaks as she goes on that her mother will take it better coming from him. Coulson starts to say it isn't over yet, but she won't be distracted, so he silently nods his assent, whereupon she asks the group if she could have a moment alone with Fitz. Skye can barely function, she's so distraught, but May kindly leads her away. Fitz, for his part, is saying that the pulse from the third rat seemed much less powerful, which would indicate progress with the "antiserum," and she's gratified that he finally used the correct term, but that doesn't stop her from saying she's sorry and bopping him on the back of the head with a fire extinguisher. He falls to the floor, but doesn't seem to lose consciousness, which is probably better for Simmons' chances but waaaay more painful.
May tells Coulson, who really looks about to lose it, that "Agent Blake" is on the line for him, and if Coulson won't answer, he's requesting Ward. Ward asks for orders, and Coulson blue-steels that they're unchanged, but an alarm goes off -- someone's lowering the cargo-hold ramp. With a panicked look, Ward rushes off, while in the lab, Fitz manages to get back to his feet -- and see that the third rat is alive; the pulse was apparently only strong enough to knock him unconscious. I do wonder if it would have floated into the air as the others did in that case, but Fitz is more concerned with yelling at "Jemma," who's standing at the edge of the now-open hold. He tries to manage the door and to scream at the top of his lungs that they were successful, but both efforts are in vain as she gives him one last fond look before she allows herself to fall and is swept away by a wind current. He screams in horror, and that's an act break!
Finally getting the door open, Fitz grabs the delivery system and rushes out, grabbing a parachute, but he clearly doesn't know what he's doing, so thankfully Ward appears and in the space of 1.2 seconds collects the parachute and antiserum and flings himself after Simmons. After he fully straps the parachute on, he gets a visual on Simmons, and contrary to her flailing, he adopts a streamlined posture that makes him look quite a bit like Superman, and I'm sure the people at DC Entertainment are laughing at Marvel for that one. After some tense moments, he manages to grab her and deliver the antiserum, and soon after, the parachute has been deployed and they're floating safely when a meager bit of electricity is discharged. But will it leave a mark?