Desmond starts crying, like a little baby. He folds up the letter, and sobs. He grabs the bottle and throws it. "It's all gone!" he screams. Then he goes over to the bookshelf, yelling and screaming and pulling the books off. And then the records. Not the records! He stops for a moment, to cry some more, and hears banging coming from somewhere above him, as well as Locke's muffled voice (not that he knows who Locke is yet). He runs down to the bottom of the shaft, and sees movement through the tiny window up top, and we hear Locke yelling, "I've done everything you wanted me to do? Why did you do this? Why?" So it's the night Boone died. And Desmond turns the light on, which we watch Locke's reaction to again. Well, at least it wasn't Desmond taking a dump. And I do think it's kind of cool that that night provided as important a sign to Desmond as it did for Locke. And Desmond starts to laugh.
Back to the present: Desmond opens the Dickens book, which is where he's hidden the failsafe key. He runs back into the computer room, where the timer is at 29 seconds. He shoves aside a cabinet, much to Locke's surprise when he sees Desmond open the grate underneath it. "Three days before you came down here, before we met, I heard a banging on the hatch door, shouting. But it was you, John, wasn't it? You said there isn't any purpose. There's no such thing as fate. But you saved my life, brother, so that I could save yours." Locke's sticking to his "none of this is real" story, and tells Desmond things are going to be okay. There's five seconds left. Desmond says he's gotta hustle, and Locke likewise needs to get as far away as possible. Locke wants to know where he's going. "I'm going to blow the dam, John," says Desmond, as the timer hits zero and starts flipping to the hieroglyphs. "I'm sorry for whatever happened that made you stop believing. But it's all real. And now I've got to go and make it all go away." Locke tells him to wait, but Desmond gives him his catchphrase: "I'll see you in another life, brother," and disappears down the tunnel.
Locke looks up at the timer, and the last hieroglyph flips into place. "System failure!" announces the loudspeaker, over and over again, as everything begins shaking and rattling. Charlie's still preoccupied trying to help Eko, and the metallic objects are starting to their little dances of attraction. Eko finally comes to, and none too soon, as several of the metallic objects, like knives and darts, could do non-metallic things, like people, severe damage as they fly down the hall towards the magnetic wall. Charlie helps Eko walk, which is quite a sight, and they barely avoid getting hit by a heavy garbage bin. Dumbbells are rolling, and stationary bikes and fire extinguishers are flying through the air. Eko pushes Charlie away so he can run back to the computer room, which Charlie doesn't seem to think is such a good idea, but then Charlie gets distracted by the washer and dryer, which are trundling down the hallway towards him.