Not long after defeating the Cyberman invasion of Earth, the Doctor, Jamie and Zoe witness a cyber-ship escaping the wreckage of their fleet, and give chase. Landing on the the idyllic planet of Isos II, they find the beautiful city completely deserted...
The Isos Network contains examples of:
- Big Creepy-Crawlies: The old subway monorail tunnels are now the home to giant, friendly slugs, who've been unwittingly holding the Cybermen at bay by stealing their power to hatch eggs.
- Continuity Lockout: If you haven't watched The Invasion, then you would have trouble understanding the beginning of the story.
- Ghost Town: The city on Isos II is completely deserted... except for the giant slugs.
- Lost Colony: A military mission from Isos shows up at the same time as the Doctor, to investigate why the Isos II colony hasn't been in contact in three years.
- Recycled Script: The abandoned city setting and giant slugs were previously used by he same author in the Doctor Who Magazine story “Food For Thought.”
- Sealed Evil in a Can: The Invasion-era Cyberleader is trying to manufacture enough power to wake a Tomb-era Cyber-Controller from stasis.
- Sinister Subway: The titular Isos network is the city's subway network, abandoned when they switched to an above-ground monorail.
- Space Brasília: From the description given, it seems clear the city of Isos II is one of these.
- Unwilling Roboticisation: Done to the entire colony on Isos II, in preparation for the invasion of Earth. Zoe's new friend Hilsee was only half-converted.
