We opened on Locke in the hospital with Jack waking him up. Locke said he knew Jack. Jack recalled meeting him at the airport. Jack asked Locke how his spinal injury had happened, because he thought Locke was "a candidate." He was talking about a new type of surgery that Jack thought might get Locke walking again. Locke refused.
Helen showed up and thanked Jack profusely for "saving" Locke.
Back on the island: Jack woke up in a canoe and found Sayid welcoming him to Hydra Island. Whidmore's men were corralling Sawyer, Hurley, Kate and the rest into cages, while setting up pylons around the cages to keep the smoke monster out. Sawyer refused to be locked up and grabbed a gun. Whidmore then showed up and threatened to shoot Kate if Sawyer didn't put the gun down. He said Kate's name was not on "the list" (Sawyer, Hurley and Sun and Jin were on the list, Whidmore noted) so he didn't care if she lived or died. Sawyer gave up and was tossed in a cage. Whidmore told Sawyer he was being locked up for his own good, then he turned and told his men to work faster in setting up the fence. "He's coming," Whidmore said.
Back in L.A.: Jack went looking for "Dr. Nadler," a.k.a. Bernard. Jack asked for Locke's medical records because Bernard had done oral surgery on him a few years earlier. Jack started to tell Bernard about how he and Locke were on Oceanic Flight 815, but Bernard stopped him and told him he was also on the flight and sat across the aisle from Jack. Bernard told Jack he couldn't give up Locke's records, but gave him the name of a man who was with Locke when he did the surgery: Anthony Cooper. "I hope you find what you're looking for," Bernard told Jack.
Back on the island: Sayid explained to Jack that the mortar attack left just the two of them and Fake Locke. Everyone else scattered and Jack's "friends," as Fake Locke put it, "got themselves captured." Fake Locke said they had to go save them. Locke wanted to move quickly so they could get off the island. Jack said he wasn't going to leave, but Fake Locke said he was still going to try to convince Jack to go. Fake Locke asked for Jack's help convincing his "friends" that they could trust him. Fake Locke told Jack he could trust him because even though he could have already killed him and the rest of the group, he hadn't.
Back in the cage, Sawyer told Kate that her name was on the wall in the cave, but it was crossed out. "He doesn't need you, Kate," he told her. Meanwhile, Sun and Jin talked about their daughter, and Sun put Jin's ring back on his finger. Suddenly, the power went out and Whidmore's men scrambled. The smoke monster appeared and took out Whidmore's guys, then Jack appeared and freed Kate and Sawyer and the rest from their cages. When Kate asked Jack what he was doing there, Jack said, "I'm with him," gesturing toward the smoke monster.
The next morning, while they all went looking for the plane, Jack told Kate he wasn't going to get on it. Sawyer thanked him for coming back for them. Sayid emerged from the jungle and said they needed to go.
Back in L.A.: Jack went to a nursing home looking for Anthony Cooper and Helen asked him to leave. She told Jack that Locke didn't want the surgery. She asked why saving Locke's life couldn't be enough, and Jack said, "Because it's not."
Jack met Anthony, who was stone-faced, non-responsive and in a wheelchair. Helen introduced him as Locke's father.
Back on the island: Fake Locke killed a couple of guys who were guarding the Ajira plane, then inspected it. He found some wires strung across the ceiling, then found something he found interesting. Frank and the gang arrived and Frank was excited to see what it would take to get it flying.
Fake Locke explained to them all that he killed the guards, but Whidmore put them up for show anyway. He said that Whidmore's real goal was for them to get on the plane, in a small confined space, then kill them. Fake Locke pulled out four bricks of C4 explosive, which he said were wired to explode when the ignition was turned. Fake Locke said the plane wasn't safe and they'd have to take the submarine if they wanted to get off the island. Sawyer agreed, but Hurley remembered that Alpert said Fake Locke wasn't supposed to leave the island. Sawyer didn't care and told Fake Locke he'd misjudged him, considering he'd "saved their asses" twice.
Fake Locke said they needed everyone to get to the submarine. Jack agreed to help, but again said he wouldn't leave the island. As they all walked toward the sub, Sawyer whispered to Jack to do him one last favor: Don't let Fake Locke get on the sub. Sawyer told Jack to "just get it in the water" and he'd take care of the rest.
Back in L.A.: Jack was waiting for Locke to wake up when Locke started muttering, "Push the button" and "I wish you had believed me." Jack was confused, but then he saw Claire out in the hall. She'd come looking for him. She showed Jack a jewelry box that the lawyer said Christian had specifically left for her. Jack said he didn't know why. She asked about Christian, and Jack told her that he'd flown to Sydney to retrieve Christian's body. She said she was just back from Sydney on Oceanic Flight 815. Claire was about to leave and Jack offered to let her stay with him.
Back on the island: They group got to the sub and Sawyer made the plan of attack. Sawyer led the first group onto the sub and took a hostage. He went to the captain. The rest of the group outside started toward the sub. Jack and Fake Locke were the last and Fake Locke tried to convince him one last time to come along, saying that whoever told Jack to stay didn't know what they were talking about. "John Locke told me to stay," Jack said, abruptly pushing Fake Locke into the water. Gunshots started to ring out and Kate took a bullet to the chest. Jack, Claire and Sayid returned fire toward the jungle as Sawyer heard the commotion from inside the sub.
Jack grabbed Kate and put her into the sub as Fake Locke emerged from the water. He walked back toward the jungle to shoot some of the attackers. Jack went into the sub with Kate and asked Hurley to get a first-aid kit. Sawyer went back up to the sub's hatch and called for Claire to get in. She hesitated and Fake Locke started running back toward the sub. Sawyer quickly shut the hatch and told Frank to have the captain "dive." Claire and Fake Locke were still on the dock. Jack was still in the sub.
As it sailed away and dove into the water, Claire called out, "They're leaving us!" Fake Locke told her, "No, trust me. You don't want to be on that sub." Kate came to and realized Claire wasn't on the sub. Jack asked for his backpack and Jin handed it to him. But what he found inside were no medical supplies. He found a bomb with a timer that was counting down with less than four minutes on the clock.
"Dude, where'd that come from?" Hurley asked.
"Locke," Jack said. "We did exactly what he wanted."
Jack said they had to get to the surface, and they sent the orders to Frank. It was going to be at least five minutes before they'd be back to the surface. Sayid was trying to figure out how to diffuse the bomb when Sawyer stepped in. Jack suddenly said, "Nothing's going to happen."
Jack explained that Fake Locke can't kill them, but what he wanted was for them to get in an enclosed space with no hope of getting out. "Locke said that he can't leave the island without us," Jack said. "I think that he can't leave the island until we're all dead." Jack then told them about Fake Locke saying he could have killed any of them at any time, "so what if he hasn't because he's not allowed to?" He wondered if Fake Locke was trying to get them to kill each other. Jack and Sawyer argued and Jack grabbed Sawyer and asked him to trust him.
"Sorry, doc, I don't," Sawyer said, before pulling two wires. The clock stopped -- but only for a moment. It suddenly started again and counted down even faster.
Sayid gave Jack instructions to the well where Desmond was hiding. "Locke wants him dead, which means you're going to need him," Sayid explained to Jack, who asked why he was telling him.
"Because it's going to be you, Jack," Sayid said, taking the bomb and running to the furthest end of the sub before it exploded. Water rushed in, with one door taking out Frank as it flew off its hinges. Jack grabbed Kate and handed her to Hurley. Sun was trapped by a metal cabinet and Jin tried to free her. Jack handed Hurley an oxygen tank and told him to take Kate to the surface.
Jin, Jack and Sawyer pulled the cabinet off of Sun, but she was trapped by more stuff under the water. Sawyer was plunked in the head by something and knocked unconscious. Jack pulled him away while Jin continued to try to free Sun. She told him to go, but he vowed to get her out. Jin told Jack to go and save Sawyer. Jack tried to give Jin an air tank, but Jin told him to "just go."
Jack left with Sawyer. Jin continued to try to get Sun loose as the water rose around them. He couldn't do it and she again told him to go, but he told her in Korean that he would never leave her again. They cried and held each other as the water continued to rise. We next saw their hands, limp, pulling apart.
Back in L.A.: Locke wasn't getting wheeled down the hall of the hospital and caught a glimpse of Jin as he walked in the other direction holding a bouquet of flowers. Locke continued down the hall and ran into Jack, who told Locke that he went to see his father. Locke was upset and told Jack that he was in a plane crash. He said he'd had his private pilot's license for a week and begged his dad to be his first official passenger. He told his dad to trust him, but something went wrong and he said the crash left his father unable to walk or talk.
Jack reminded Locke that he'd told Jack to let his father go. Jack told Locke that he could punish himself as much as he wanted, but it wouldn't bring his father back. Locke still refused and as he wheeled himself away, Jack called out, "I can help you, John. I wished you'd believe me." Locke paused, but said nothing and left.
Back on the island: Jack came to the shore with Sawyer, who was still unconscious. Hurley and Kate walked over and Kate hugged him. Jack said Sawyer was still breathing. Kate asked about Jin and Sun and Jack just shook his head softly. Kate wept and Hurley sobbed more loudly. Jack walked away and cried, as well.
Fake Locke looked out at the water and told Claire, "It sunk."
Claire asked if they were all dead, and Fake Locke said, "Not all of them."
He grabbed his backpack and a shotgun and walked off. When Claire asked where he was going, he said, "To finish what I started."