The Early Adventures: The Isos Network
The Doctor, Jamie and Zoe are leaving Earth after having successfully defeated a Cyberman invasion… The Cyber-fleet is still exploding… But something is escaping through the mass of vaporising debris.
In hot pursuit, the Doctor and his friends find themselves drawn to a mysterious planet where strange beasts slither through the streets of a deserted city… And an old enemy lurks beneath the streets.
As a force of heavily-armed aliens arrives, a battle to save the entire galaxy from invasion begins.
For the three travellers, this story takes place a few days after the Cyber-invasion of Earth. (The Invasion)
Jamie later recalled facing the Cybermen on Isos when he encountered the Sixth Doctor. (Last of the Cybermen)
The Cyber-Controller accesses the repository of cyber-experiences (Iceberg) and sees the Doctor as a white-haired old man. (The Tenth Planet) This reference raises additional questions as to the decade that The UNIT stories are set in, as the First Doctor‘s encounter with the Cybermen takes place in 1986, yet this story takes place only days after the Second Doctor‘s latest encounter with them. (The Invasion)