The spirit of "Jacob" asks who among them would become Protector of the island, and "Jack" volunteers. At the waterfall cave, "Jack" drinks the water of immortality and returns to the group. "Jack" says they must meet with "Locke" and "Desmond" to settle the dispute and kill "Locke". The 2 groups meet on the hilltop, and just the 3 proceed toward the waterfall cave. There, "Desmond" descends on a rope into the cave, but pulls a rock from the bottom, which puts out the light of the power source. The island begins a series of earthquake tremors, to fall into the sea, with rocks tumbling into the water. "Locke" flees the area, now needing to get the sailboat to the other island: he has lost his immortality when the light source was put out. "Jack" chases him to the sea cliffs to stop him from leaving, and a long fight begins. "Locke" grabs a knife and stabs "Jack" in the side, then forces the knife up to "Jack's" neck. Before plunging the knife, a gunshot is heard: "Kate" as promised, has shot "Locke" (the Smoke Monster) in the back, and "Jack" pushes him off the sea cliff, to die on the rocks below.