During the overnight flight to DeltFall, Mensah assigns watch rotations, which gives SecUnit a chance to go on standby and watch entertainment. Ratthi then asks about bot units being made from cloned human material and argues that SecUnit has feelings and is enslaved. The conversation upsets SecUnit badly enough that it retreats to the back of the hopper, while Overse and Mensah shut Ratthi down.

Later, the comm satellite suddenly stops responding, cutting the team off from the habitat and hub systems. Even though the outage deepens SecUnit's sense that something is badly wrong, Mensah asks for a group decision and the team chooses to keep going because DeltFall may still need help. SecUnit reluctantly accepts the decision and waits for arrival.

At dawn, the rescue team reaches DeltFall and finds an intact, silent camp with no movement, no exterior damage, and no response from the habitat or from DeltFall's three SecUnits. Because the perimeter systems are dead and the situation looks suspicious, SecUnit advises landing outside the camp, has the humans arm themselves, and goes in first while Ratthi stays in the hopper. Inside the first habitat, SecUnit finds one dead SecUnit and eleven murdered humans, then concludes the attack came from inside and orders Mensah's group to fall back because active hostile units are probably still present.

As SecUnit clears the camp, it finds more bodies and notices signs that a corpse has been recently repositioned to lure rescuers into an ambush. Working through the feed, SecUnit has Mensah pretend to approach from the obvious route while it circles across the roofs and enters from above. That maneuver lets SecUnit surprise two waiting SecUnits and disable them, but before SecUnit can finish clearing the area, a hidden attacker knocks it offline, strips away part of its armor, and inserts something into the port at the back of its neck.

SecUnit regains function while being handled by the hostile unit, breaks free, and kills it in close combat. A second SecUnit appears with a projectile weapon, but Mensah arrives behind it and kills it with the hopper's sonic mining drill, then helps drag SecUnit back to the hopper with Overse and Ratthi. Once airborne, SecUnit realizes the object in its port is a combat override module like the one that must have been used on DeltFall's SecUnits, and that it is already downloading commands that will turn SecUnit against the humans. Because there is no time to remove it safely, SecUnit tells Mensah to kill it and, when the team hesitates, shoots itself in the chest to protect them.