The Doctor and Ace on a planet where happiness is enforced. A giant man of candy executes Killjoys and the Doctor sings. Happiness will prevail!
The Doctor and Peri face off against a mutant dictator despite interference by future time travel "expert," H. G. Wells.
The story Old Who has been waiting for - Cybermen in the hold, drunk aunties in the Captain's chair, and Adric out the airlock.