The Flashforward tracks Jack and Kate living together and their engagement. Back on the Island, we see when Kate realizes that Jack is in love with her, all while dealing with the fact that he has to have emergency surgery for appendicitis. The ending was another one of those crazy wtf endings with Claire disappearing into the Jungle night with Jack's father (and her's) Christian Sheppard. Back in the Flashfoward there is another cliffhanger in Kate doing something for Sawyer, but she won't tell Jack (or the TV viewing audience) exactly what it was. Great episode.