While exploring an abandoned testing office Ryan inadvertently activates a set of five prototype "sec hunters": androids programmed to identify a target by their DNA and then hunt them ceaselessly. Ryan only becomes aware of this several hours later, when the first 'droid appears and tries to kill him. The sec hunter proves all but impervious to gunfire, but with some difficulty Ryan manages to destroy the 'droid by pushing it off the edge of a cliff. His victory is short-lived, as a few hours later the second sec hunter attacks, nearly killing him while he sleeps. After defeating the second hunter, Ryan heads to the test chamber to meet the third as it activates; eventually it does, but malfunctions spectacularly, attacking and destroying itself. The fourth and fifth sec hunters do not activate, and Ryan cautiously departs with the hope that the onslaught is over. Ryan makes his way down the treacherous mountain path and is eventually forced to seek shelter from a harsh blizzard. He finds the entrance to an abandoned mine tunnel, occupied by Kate Webb and her elderly grandfather Cody, two slaves who have escaped from the mine but have discovered they have nowhere to flee to. Cody is abruptly killed soon after when the fourth sec hunter emerges from the blizzard, following Ryan and killing Cody because he was in the way. Kate and Ryan flee deeper into the mine, eventually losing the 'droid by jumping over a large chasm blocking the tunnel. Venturing deeper they discover a fast-moving underground river, which unexpectedly swells and draws them into it. They are briefly stopped by a net strung across the river by "trackies" - hostile mutants - and after nearly being killed by a large group of them Kate and Ryan take their chances in the river again. When they finally find themselves outside again and on land Ryan narrowly manages to get both of them to the shelter of a small cave and start a fire before they succumb to the cold. Grateful for him saving her life, Kate seduces Ryan into having sex with her. Back in New Mexico Jak has returned safely home. During breakfast one morning he mentions that Christina has been ill recently; at Doc Tanner's questioning he confirms that his wife has been sick only in the mornings, but fails to understand the significance. Sometime later the companions notice a