Contains spoilers for this episode and earlier episodes.
Flashbacks show Kate entering a New Mexico bank as an apparent customer before an armed robbery begins. She seems to be a hostage, but a private kiss reveals her involvement with one of the robbers. Their confrontation with the manager exposes her real plan. Kate shoots her accomplices and demands access to safety deposit box 815, taking an envelope from it instead of the cash the other men had come to steal.
On the island, Kate and Sawyer find a locked case among submerged aircraft seats and bodies. Sawyer keeps it when Kate refuses to explain why she wants it, and her attempts to take it back fail. She tells Jack it contains the marshal's guns and that the key is buried with him. They dig up the body, but Jack catches her concealing the key. He then pressures Sawyer to surrender the case by threatening to withhold antibiotics.
Jack opens it with Kate and finds weapons and an envelope containing a toy aeroplane. Kate says the toy belonged to a man she loved and killed, but offers no complete account of what happened. Elsewhere, Rose prays with Charlie as he struggles with Claire's disappearance, and Shannon recognises Rousseau's notes as lyrics to La Mer. The survivors move their beach camp away from the advancing tide while Kate sits beside the fire holding the recovered plane.