At the very least, this episode certainly shows us why Robin Hinton always seems so scrambled. Its structure bounces back and forth between present day on the dilapidated Zephyr, where Coulson and the others are trying to figure out a way to save the world, and the past, where a child-aged Robin watches as humans transition from life on Earth to life on the Lighthouse, for reasons that don’t become clear until the very end. So let’s try to untangle this timey-wimey ball.
We start with Robin as a kid, on a much-less-rusty Zephyr. Simmons and May are trying to pilot the ship through a gravity storm, so this must be shortly after Daisy quaked the world apart. Robin says they’ll survive the crash, but notes that “there’s something else I need to remember.” She has the same problem in the present. As an old woman, Robin is even more enigmatic than she was as a young girl. One of the surviving humans living in the Zephyr with her, a man named Voss, says that she can’t separate past, present, and future. For instance, he’s about to head out to bring the rest of May’s friends on board, and he knows where they’ll be because Robin told him — a decade ago, that is. Coulson is currently in the midst of crashing the ship they stole from Kasius, but all the S.H.I.E.L.D. members survive the crash, just as young Robin predicted years earlier.
Coulson is eager to get any and all information that might help his team return to their own time and prevent this apocalypse from happening, but Robin isn’t very forthcoming. All she’ll tell him is that he’s the one who can bring all the pieces together, and that “this is the day it all ends.” Coulson and May appeal to Enoch for help communicating with Robin, but Enoch says she was only ever chatty with her mom; he has sometimes been able to get things out of her by staying at her side for days, but time is not a luxury they have anymore.
Meanwhile, Fitz and Simmons find the machine used to activate the white monolith and bring them all here. They’ve even found a piece of the monolith, but apparently that’s not enough. If they could find more, perhaps they could reconstruct the portal and go back in time to stop this all from happening. But while they try to figure that out, Fitz and Simmons finally find themselves with some alone time, and put it to good use.
Returning to the flashbacks, we see how things started to fall apart. As a young Robin wanders through the halls of the early Lighthouse muttering Flint’s name over and over, Yo-Yo and May get into a fight about whether to rebel against the Kree, who are apparently still in the early stages of running the station. Yo-Yo wants to overthrow them before they enslave the human survivors, but May puts all her trust in Robin, who says they can save the world.
As time went on, apparently May was the only one who kept faith in Robin’s prophecies. Fitz got frustrated that all their attempts to prevent the cataclysm failed, returning him to his old idea that time is unchangeable. He even says that the Daisy who went into the future came back and still destroyed the Earth — Robin couldn’t change it, and Voss couldn’t change it. If you’re not good at keeping time travel straight in your head, this is probably starting to get a little unwieldy.
Back in the present, we soon find out what Fitz meant by Voss’ attempt to change the timeline. Though he’s a longtime friend of Robin’s, Voss clearly doesn’t trust all of her prophecies. While they’ve got Daisy with them, he and his fellow survivors decide to try killing her — the only definitive way they see to change the timeline. Naturally, tragedy occurs. As Daisy fights her assailants, Robin wanders into the crossfire and gets fatally stabbed. This is what she meant when she said this was the day it all ends — for her, at least.
This triggers the last flashback, to May rocking a child-aged Robin to sleep as a surrogate mother. One day, May says, you’ll have to tell me how to fix this. The young Robin has’t seen it yet, but the older Robin has, and as she dies she whispers to May the way they can go back in time, because no Hinton can die without whispering one last prophecy on their way out. Returning to the others with the news, May only has one question: Who’s Flint?
Flint, meanwhile, has been brushing up his revolutionary bona fides by rescuing the Lighthouse inhabitants from Kasius’ unleashed roaches and helping them stand together against the Kree’s manipulations. And with that last hint from Robin, it sounds like his rock-manipulating abilities are going to be just as central to reconstituting the Earth as I suspected…