Jack tries to help the wounded Boone. Everyone else seems shocked and he has to yell at them to get them to help. He sends Kate to get Sawyer's alcohol for Boone.
FLASHBACK: Jack is helping his friend Mark with his tie, as he is about to give a speech...the tailor comes back, and says "grooms turn" to Jack.
On the Island, Jack tells Boone he won't let him die. It's the next day at camp. Sawyer, Michael, Walt, and Claire are around the fire while Jin is continuing to work on the raft. It will be ready in about a week. Sawyer claims Claire likes him. Michael tries to get Jin to take a break but he won't. Kate comes running and takes all of Sawyer's alcohol for Boone. Sawyer offers to help but Kate tells him there are too many cooks.
Back at the tent, Jack realizes Boone needs a transfusion - he starts preparing but Sun tells him to get some air. Charlie wants to know what has happened and where Shannon is.
FLASHBACK: It's Jack's wedding. Mark introduces Jack's wife - turns out she was hit head on by a car and broke her back, Jack promised to fix her and succeeded. Now she can dance at her wedding and she proposes a toast.
Back at the tent, Sun has a stick for Boone to bite down upon, as Jack relocates his broken leg and Boone howls in pain - Hurley covers his ears outside.
Kate is running back and trips. She opens the bag; some of the alcohol bottles have broken. She hears a noise and goes to investigate. Kate finds Claire in labor. Claire says it's just a false alarm but Kate calls for help. Jin hears her call, runs through the woods and finds them. Kate gives him the bag and tells him to get Jack.
Jack and Sun try to get Boone's blood type from him for the transfusion. He is A negative. Jack tells Sun to ask everyone else for a match and to get Shannon.
Shannon and Sayid are in the jungle. She thinks he is lost but Sayid leads her through a clearing which brings them out at the beach. He has set up a picnic for her!
Charlie comes back to the tent, he was only able to find 4 people who knew their blood type. Jack reveals he is O negative (universal donor) but it could send Boone into anaphylactic shock. Sun presents a sea urchin. Now they have the right kind of needle for the transfusion.
FLASHBACK: Jack plays the piano when his fiancee, Sarah, comes up. He is having a hard time with the vows. She tells him he doesn't have to go through with it but he wants to he just has to find the right way to say it. They kiss and Sarah goes upstairs (we see the back of her T-shirt has the number "44" on it).
Back at camp, Jin runs into the tent and through Sun tells Charlie and Jack about Claire. Jack tells him to take Charlie back and to tell Kate that she will have to deliver the baby because he will not leave Boone.
Claire's contractions have stopped but Kate doesn't think it's over. Sure enough, her water breaks. Claire says she can't have the baby now, but Kate reassures her by telling her Jack is coming.
Boone becomes briefly conscious and tells Jack he was in a plane and something about a hatch...Jack wants to know more but Boone falls unconscious again.
Shannon and Sayid are making out but she pulls back. She tells him Boone is actually her stepbrother, and he is in love with her. Sayid asks if she is in love with Boone and she says she will always feel something for him just not in that way. Still, she needs to take it slow.
Charlie and Jin arrive back with Claire and Kate. Kate wants to know where Jack is to which Charlie explains that Jack isn't coming, and she has to deliver the baby herself. Claire is scared something happened to the baby while she was captured by Ethan. Jin and Kate are scared too but try to calm her. The transfusion at the tent isn't working; the blood is pooling in Boone's leg. Sun pulls out the line because Jack has given enough blood. Jack send Hurley to get Michael at the beach
FLASHBACK: Jack is sitting at the pool trying to write his vows. His dad arrives and reads what he has so far. It turns out they are Sarah's vows that Jack stole. His dad asks if he loves her to which Jack answers absolutely. But Jack is worried about being the perfect husband or father. His father tells him how commitment is what makes him tick but he needs to let go.
Back at the tent, Jack talks to Michael about the need to amputate Boone's leg using the cargo hatch.
Kate wants Claire to push but Claire is panicking. She thinks the baby will know that she planned to give it away for adoption. Kate tells her it also knows Claire wants it to be healthy and safe. Claire pushes. Charlie goes to help but Jin holds him back.
Meanwhile, Boone coughs up blood as Jack prepares to move him. Sun knows that he is bleeding inside and tells Jack he isn't helping him and can't save him. Jack won't listen. He tells Michael he doesn't him want to see this but Michael knows he needs him to shut the hatch.
FLASHBACK: It's Jack's wedding day. Sarah has just delivered her vows. But Jack didn't write any vows - he couldn't because he's not good at letting go. Her words were very beautiful and he says that she fixed him. They kiss.
Back in the caves, Jack is about to send down the door to cleave off Boone's leg but Boone stops him. Boone tells him to let go there is no chance. Jack apologizes that he can't save him.
Kate can see the head of Claire's baby. It's a boy! Claire holds the crying baby and is overjoyed. Boone tells Jack to tell Shannon....tell Shannon...but he dies before we hear the rest. Jack closes Boone's eyes.
Claire arrives back at camp with her baby and everybody is happy to see the baby. Hurley taps Jack on the shoulder to indicate that he sees Sayid and Shannon coming back from their candlelit tryst. He tells Shannon about Boone and Shannon cries over Boone's body. Kate finds Jack and asks if he wants to talk about Boone to which Jack responds Boone didn't die. He was murdered. And sets off to find Locke...