The newly-regenerated Doctor helps UNIT battle a sentient robot being manipulated by a corrupt scientific organization.
The Third Doctor and Sarah arrive in 1970s London to find it has been evacuated because dinosaurs have appeared mysteriously. It turns out the dinosaurs are being brought to London via a time machine to further a plan to revert London to a pre-technological level.
On the jungle planet Spiridon, the Doctor, Jo and a Thal group find a slumbering army of Daleks ready to awaken.
