After a skirmish with an alien warrior in the Middle Ages, Sarah Jane Smith's life as a journalist in Croydon seems rather tame. She decides to track down the enigmatic character who took her back in time; with the Doctor, a good story is never far away. Her intuition pays off. The Doctor and UNIT are called to investigate a grisly murder at Space World, a futuristic new theme park. Tagging along, Sarah and her new colleague Jeremy soon find themselves facing huge crab-like creatures, mind-controlling devices and viscious flesh-eating beetles. And those are just the attractions ...

This is an adaptation by Barry Letts of his own radio play, in which Jon Pertwee, Elisabeth Sladen and Nicholas Courtney reprised their roles as the Doctor, Sarah, and Brigadier Lethbridge-Stewart. Barry Letts is the writer of several of the scripts for the TV series, and was producer of the show from 1970 to 1974.
 

Jon Pertwee returns as the renegade Timelord reunited with Sarah Jane and the Brigadier by author Barry Letts the producer behind so many of his adventures. And he is facing more danger than ever ...

When an horrific and inexplicable death occurs at "Space World", a new theme park at Hampslood Heath, Brigadier Lethbridge-Stewart and UNIT are called to investigate. The Doctor is highly suspicious. Just who controls Parakon Corporation, the shadowy organisation behind the running of the park? What is "Experienced Reality"? And what are the limits of its awesome powers?