Sayid welcomes Jack to Hydra Island and gives him a recap on being attacked by Widmore's camp. MIB/UnLocke/Smokey demands Jack's help to rescue the Losties in the polar bear cages so they can leave the Island. He promises that he can and will kill them all if he doesn't.
Widmore's men try to put Sawyer in the polar bear cage and he refuses in his gorgeous Southern accent to get in those cages again. Widmore reveals that he has a list with Sawyer's, Jin's, Sun's and Hurley's names on it. Where did he get the candidate list? He threatens to kill Kate and quite expectedly Sawyer allows himself to be locked once again in the polar bear cage.
Sawyer reveals that Kate's name was crossed out in the cave and Widmore was speaking the truth when he said that he didn't need her. She looked a bit rattled by that news. Smokey passes through to do his destructive thing. And Hero Jack comes and sets the Losties free.
Jack reaffirms to Kate that he won't be getting on the plane with them. She looks slightly disappointed. Sayid comes in and leads them all in the plane's direction. They show up to find MIB/UnLocke/Smokey is already there and had broken a couple necks already. MIB/UnLocke/Smokey reveals blocks of C4 on the plane that presumably would blow them to bits if they tried to leave in the plane.
So he proposes the submarine instead. And off the trot to steal Widmore's submarine. Only Sawyer has another idea and enlists Jack to help him get rid of MIB/UnLocke/Smokey.
They scamper into the submarine. Jack shoves MIB/UnLocke/Smokey into the water. Kate gets shot. The rest except for Claire who's busy shooting Widmore's men climb into the submarine. Sawyer closes the hatch and orders a dive leaving MIB/UnLocke/Smokey on the dock.
Claire's upset at being left behind. Again. MIB/UnLocke/Smokey wryly reveals that she doesn't want to be on the sub anyway. In an effort to fix Kate, Mr. Fix-It Jack asks for his pack where he discovers the C4 connected to a timer. Clever ploy MIB/UnLocke/Smokey.
Jack insists that they're going to be fine. Sawyer doesn't have quite the same confidence and pulls the wires out of the bomb. Only it quickens the timer. Sayid instructs Jack on where Desmond is and that he has to get him because MIB/UnLocke/Smokey wants him dead. Then Sayid grabs the bomb and runs to the other end of the sub.
They start taking on water fast. Hurley takes Kate out. Jack, Sawyer and Jin try to free Sun who has been trapped by some debris from the blast. They remove one thing to discover she's pinned even further. Jin insists Jack take Sawyer out who is now unconscious from hitting his head.
Jin refuses to leave Sun and they die together in the submarine in a touching scene that if I had cared more about the characters I probably would have cried. But since I've never really liked Sun, I didn't.
Hurley, Kate, Jack and Sawyer crawl out onto the beach. And pause for a moment to grieve for Sun and Jin.
MIB/UnLocke/Smokey can tell that the sub sunk and not all of the died. He storms off to finish the job.
Locke wakes up after surgery to find Jack who proclaims him a candidate (nice choice of words) for a new surgery that could restore his ability to walk. Only Locke's not interested in walking again. Interesting as our Locke would have jumped at the chance. Oh, Jack the perpetual fixer, some people don't want to be fixed.
Not to be deterred, Jack goes to Bernard to get a medical file on Locke. They discover that they were on Oceanic 815 together (oooo, the hairs stand up) and Bernard gives Jack the name Anthony Cooper.
Jack goes to visit Anthony Cooper and runs into Helen who pleads with him to leave well enough alone. But Fix-It Jack can't do that. Helen introduces him to Cooper, Locke's daddy. Cooper looks like he's missing a few crayons in his box. Blank stare, slightly drooling. The Sideways accident was clearly a little different than the one we saw.
Jack is back in Locke's room to talk to him presumably about the accident and/or the surgery that is supposed to make him walk again. Locke coming out of a nappy nap starts rambling about a button and wishing Jack had believed him. Jack looks confused and then spots Claire outside asking for him.
As they chat about their father and what he willed to Claire, they realize they were on the same flight back from Sydney and look like they got a big case of deja vu. Jack asks Claire to come stay with him because they're family. Jack finally seems to be getting the concept of family.
Locke is being released from the hospital and Jack goes to say goodbye and try one more time to talk to him. Locke reveals it was a plane crash that caused him to lose his ability to walk. That he had convinced his father - who apparently he had a great relationship with - to be his passenger and he's the reason why his dad is pretty much a vegetable. Jack tells him that he should let go and forgive himself and declares that he can fix him.