An alien life pod is ejected ten miles from the impact zone of a Judoon spaceship and crashes into an abandoned council estate.
He uses the supercomputer in Sarah Jane's attic, Mr Smith, to access the schematics of a spaceship that the United States military re-engineered from the debris at the Roswell incident.
Assisted by the Judoon Captain Tybo, Luke, Clyde, and Rani follow the possessed Sarah Jane and Androvax to the nanotechnology company.
The Judoon charge Clyde and Rani with interference, but take the pair's assistance and motives as mitigating factors, limiting their punishment to a bar against extraterrestrial travel.
Pearson Education published a simplified novelisation of this episode by Trevor Baxendale under the title Judoon Afternoon for school literacy programs in September 2010.