A man awakens to a beeping computer. He inputs some numbers, presses "execute," which causes the beeping to stop. As he goes about his morning routine, accompanied by Mama Cass' "Make Your Own Kind of Music", there is an explosion. He puts on a jumpsuit, grabs a gun, and looks down a scope system to see Jack and Locke, looking down into the Hatch. The two argue about what to do next, with Jack insisting they won't be able to get everyone in. Locke, in his everlasting insightfulness, asks Jack why he doesn't want to go into the Hatch.
FLASHBACK! A woman is wheeled into the ER after a horrific car crash. Jack comes down and quickly get to work stabilizing the patient. Another patient, one Adam Rutherford, is brought in as well, but there's not enough time for Jack to work on both patients. He decides to focus on the woman, successfully stabilizing her while Mr. Rutherford unfortunately dies. Jack orders the woman to be taken up to ICU, as she mutters "I need to dance at my wedding..."
Meanwhile, everyone is back at the caves. Charlie tries to convince them that no one is coming, that Danielle is totally nuts. He tries to get reassurance from Sayid, who's not convinced. Back at the Hatch, Hurley asks Locke why he lit the fuse, even as he was waving his arms and screaming "Don't light it!" Locke says he was simply excited to get in, claiming it was the reason why they did everything they did, including, as Jack reminds him, to save everyone. Kate takes a look at the blasted door, and sees the word "QUARANTINE" stenciled on it. At the caves, Shannon goes off into the jungle because she can't find Vincent, and instead finds Walt, soaking wet, whispering something...On their way back, Jack asks Hurley what he meant by "the numbers are bad." To this, Hurley tells him his story about the psych ward and winning the lottery, and the long string of bad luck that followed. After saying the numbers on the Hatch are the same numbers he played the lottery with, all Jack can say is "You were in a psych ward?" before being told that his bedside manner totally sucks.
FLASHBACK! We see the Dr. Jack Bedside Manner in action, as he bluntly tells the woman, Sarah, that it's highly unlikely she'll ever regain any mobility below the waist. He then gets chewed out by his father, who points out that providing hope is crucial for patients, but Jack is against selling false hope.
At the caves, Shannon tells everyone that she saw Walt, but finally Jack arrives to reassure them. He tells them about the Hatch, and that Dr. Arzt was killed, and reminds them that while their plan can't work now, they still have guns and will all see the sun rise. However, Locke has tuned him out and takes an large amount of cable wiring to climb into the Hatch. Kate decides to go with him.
FLASHBACK! Jack explains to Sarah's fiancÚ, Kevin, about the surgery. However, Kevin gets visible uncomfortable about what lies ahead, how Sarah will require professional care for the rest of her life. As Jack preps for surgery, Sarah assures him that she knows she'll never dance again, and that he's invited to the wedding. To this, Jack makes a promise: "I'm gonna fix you."
Locke is still prepping to climb into the Hatch as Kate arrives. After convincing her to go first, because she's lighter and because Locke doesn't want to be the first to be eaten by whatever's down there, there is a bright light and Kate vanishes. Meanwhile, Jack decides to go after them, but finds neither of them at the Hatch.
FLASHBACK! Jack is running up and down the steps at a stadium, trying to clear his mind. He spots another runner, who proceeds to race him up to the top, until Jack falls and sprains his ankle. The runner, Desmond, provides some help and explains that he's training for a race around the world. The two chat, with Jack talking about the girl he couldn't fix, but Desmond is hopeful that he did. The two part ways, with Desmond saying "See you in another life."
Jack climbs down into the Hatch. Inside, he finds a concrete bunker and evidence of habitation. He sees the computer from the opening, and is about to press the "execute" button, but is warned off by Locke. As Jack draws his gun, the man in the Hatch aims one at Locke's head.
FLASHBACK! Sarah is in recovery and Jack is at her side as she wakes up. She asks where Kevin is, before both realize he's left and isn't coming back. As Jack reiterates how she will never walk again, she claims she's able to move her toes. Jack fixed her!
Back in the Hatch, there's a standoff. Jack chides Locke a little about how this was his "destiny," at which point the man in the Hatch threatens to "blow his damned head off, brother!" The man in the Hatch is Desmond!