This story survives only in still pictures and fragments. It is extremely unusual in that none of the normal cast appear, including The Doctor. It was only one episode in length. On the planet Kembel, two members of the United Nations Deep Space Force Group One are attacked in their damaged spaceship by a crew member who awakes in the jungle in a state of homicidal rage.
The Deep Space Force is investigating the possibility of a Dalek base being established on the planet. Indeed, the Dalek Supreme has brought together representatives from the Seven Galaxies. The entire human cast dies and the Daleks’ plans go into effect.
The story happened because long-time producer Verity Lambert wanted to give the cast an extra week’s vacation. The one-off episode served as an intro to the later twelve-part story The Daleks’ Master Plan. The writer, Terry Nation, was thinking of a series about a Dalek-hunting Space Security Service.