Tom Campbell, a policeman, accidentally enters the TARDIS and is transported to 2150 A.D. by Dr. Who, only to find a desolate world controlled by the ruthless Daleks.

Daleks' Invasion Earth 2150 A.D.
In 2150 AD, the Doctor and his companions find a desolate Earth, having fallen under the tyrannical control of the Daleks, who hold its inhabitants captive.