Series 2, Episode 2
As Jack descends into the hatch to find Kate and Locke he finds himself confronted with an armed man, whom he recognises from a previous encounter at the football stadium. Out at sea Michael and Sawyer battle for survival during the night despite their arguments. The flashbacks deal with Michael's unsuccessful custody battle over Walt.
Look out for some tasty flesh shots of Kate as she jumps for ventilation grill and then crawls through a shaft. Very deliberate if you ask me!