The serial The Paradise of Death was first broadcast in five episodes on BBC Radio 5 (a station which, at the time, was heard solely on AM in the UK) from 27 August to 24 September 1993.

Letts was thereupon commissioned, instead, to develop an idea for a radio play based upon the 1970s BBC science fiction series Blake's 7, which would ultimately lead to his writing two productions featuring cast members from that show, which were broadcast in 1998.

Brigadier Lethbridge-Stewart of UNIT asks the Doctor to investigate a particularly gruesome murder at a new theme park on London's Hampstead Heath, called Space World.

Together with journalist Sarah Jane Smith and her photographer Jeremy Fitzoliver, they take in the incongruous exhibits, including virtual reality machines, and even seemingly living alien monstrosities – which the Brigadier immediately suspects of the killing.

The owners of the theme park are a gang of alien carpetbaggers from outer space, who are ostensibly trying to persuade the Government to begin talks on allowing interplanetary trade.

When Sarah is kidnapped by the sinister Mr Tragan, and transported to the aliens' home planet, Parakon, the Doctor and the Brigadier must race to her rescue in the Tardis.

Freeth and Tragan are secretly conspiring to overthrow the President and democratic government on Parakon, and fear what the visitors from Earth may accidentally disclose which might reveal their plans to Captain Rudley, the commander of the Presidential Guard.