When the TARDIS lands in a dilapidated attic, the Doctor, Vicki and Steven discover they are on Earth, in London... in Number 10 Downing Street.
However alien forces are at play here, affecting the very fabric of the building... and adjusting the very essence of history itself.
Written By: Mat Coward
Directed By: Lisa Bowerman
Maureen O'Brien (Vicki), Peter Purves (Steven)