Departure from Telos was one of the Cyber-Documents, a set of audio-visual documents originating from Earth, which were compiled into the CyberHive. Designated Document 9, Departure from Telos was an account of the Cybermen's attempt to leave the planet Telos. (AUDIO: The Ultimate Cybermen)
Behind the scenes
Departure from Telos corresponds with the Doctor Who story Attack of the Cybermen.