The Drashig moves past them and the Doctor realizes it is blind and following their scent.
Kalik is intrigued by the Drashigs, especially when Shirna tells him about a past expedition that was completely destroyed by the creatures.
The Doctor and Jo retreat to the cave only to find three Drashigs waiting for them. The Doctor uses his sonic screwdriver to ignite the swamp gas but that only holds them off for a little while. Eventually, at Shirna's and Kalik's urging, Vorg puts his hand in and bats the Drashigs away, allowing the Doctor and Jo to escape.
The Doctor realizes that they are inside a Miniscope, being confined for someone's amusement. The machines are supposed to have been banned.
The Drashigs begin to follow the Doctor and Jo's scent. They break out into the internal workings of the scope.
Pletrac wants to deport Vorg and Shirna immediately but Kalik persuades him to take his time and follow the correct procedure.
The Doctor and Jo continue to flee into the circuits. But the Drashigs continue to pursue them. Shirna realizes what has happened and tells Kalik. He confides to Orum that he expected this. He is hoping that the Drashigs will escape and that the ensuing chaos will allow him to overthrow the government.
The Doctor and Jo find a deep shaft that leads to the outside. Jo hits on the idea of returning to the ship for some rope to climb down. They return to the cargo hold but Jo is caught by Andrews.
Jo talks to the Bernice's passengers and tries to explain what's really happening and force them to remember. Claire seems to have a glimmer of understanding but it quickly vanishes.
One of the Drashigs follows the Doctor and bursts into the hold of the Bernice. Andrews and the crew attack it with rifles.
Kalik sends the Functionaries away and removes the trigger from the eradicator. Pletrac reports that the President has agreed to order the aliens removed from the planet.
A Drashig bursts through the top of the ship and the Major destroys it with a machine gun. Andrews lights sticks of dynamite and attacks the remainder. He kills the Drashigs but damages the Miniscope, which begins to fail.
Andrews returns to the cabin to take Claire for a walk. He and the passengers have now completely forgotten all about the Drashigs and Jo.
The Doctor takes a rope from the hold and descends through the ventilation tube, where he finds the body of a Drashig. He emerges from the Miniscope and collapses…