Transmitted originally: 8 March 1982 to 16 March 1982.
The Doctor, his companions, the surviving troops and Professor Kyle of the scientific expedition follow in the TARDIS, the bomb's activating signal to and approaching space freighter. The ship, commanded by a Captain Briggs has on board a hidden army of Cybermen, ready to attack Earth. An attempt by Adric to thwart the Cybermen's plans result in the freighter being thrown back millions of years into the past, where it explodes and causes the extinction of the dinosaurs - as well as the death of Adric. The Doctor destroys the Cyber Leader by forcing gold fragments from a badge previously worn by Adric into its chest unit.
A sequence of clips from earlier stories is used as the Cyber Leader discusses some of the Doctor's past encounters with the Cybermen.
The Fifth Doctor Novelisations