The Seventh Doctor and Ace respond to an invitation to visit the mysterious Psychic Circus on the planet Segonax, despite Ace’s fear of clowns and reluctance to go. Other travellers have arrived on the wasteland world too – the fannish Whizz Kid; the motorcycling maniac Nord; tiresome bore and intergalactic explorer Captain Cook and his companion Mags, whom the Captain curiously refers to as a "unique specimen".
But all is not pleasant outside the circus tent. The clowns are all mechanised apart from the human Chief Clown, who travels around in a hearse and recaptures an errant robot repairman Bellboy when he tries to escape. His companion in flight, Flower Child, is killed by something mysterious aboard a disused hippie bus. It turns out to be a robot conductor which also attacks the Doctor, Captain, Ace and Mags. The Doctor destroys the killer robot, while Ace finds one of Flower Child’s earrings and pins it to her jacket as a keepsake. They venture on to the circus tent itself, but Ace hesitates. She thinks he hears screaming which is Mags who is already in the Circus and is seeing the clowns kill somebody. Outside, the impatient doctor inquires:Are we going in, or aren't we?
The Doctor learns from Morgana the ticket seller that the Circus was founded by hippies as part of their artistic expression. They both join the audience, noticing the only other observers are a small family of three – father, mother, daughter – who observe the central stage with stoic disdain. The Ringmaster soon appears and invites the Doctor to join the entertainment. He agrees and is taken backstage where Nord, the Captain and Mags are also being kept. It appears that audience members are expected to become part of the show. Nord is duped into performing first and when his act fails to amuse he is obliterated.
The Chief Clown meanwhile interrogates Ace as to where she got the earring, suspicious of the girl. She flees deeper into the circus and finds Bellboy strapped to a work bench. She hides as the Chief Clown frees him and then ventures back to the main entrance where she sees Morgana and the Ringmaster arguing about the Circus. He does not share her ethical qualms about the means used to fill the Circus. Their argument is interrupted by the arrival of Whizz Kid, who is ushered into the ring. He too is obliterated when he fails to please.
The Doctor and Mags venture deeper into the Circus and find a vast well shaft which illustrates a pulse of energy at its core. A curious eye symbol can be found there which is also depicted at the heart of a crystal ball owned by Morgana, inspiring her to pledge her loyalty to the forces that control the circus.Then the Captain enters with a group of robotic clowns, telling the Doctor it is his turn, and he is in the ring.
Ace has meanwhile met with Bellboy, who tells her more about the origins of the circus. One of the workers, Dead Beat, was once called Kingpin and brought them to Segonax in search of a great power which has now gone horribly wrong. The death of Flower Child was at the hands of a robot he built himself and he feels wracked with guilt. When the Chief Clown arrives to recapture him, Bellboy sets a reprogrammed clown on himself and it kills him.
The Doctor has meanwhile escaped and encountered Dead Beat and realised he is key to the situation. They find Ace too and together they visit the well again. Dead Beat has a medallion embossed with the image of the eye which is missing a piece and Ace and Dead Beat head off to the bus to try and find it. The Doctor returns to the circus proper and finds himself in the ring with Mags, but Captain Cook is one step ahead. In an effort to ensure a good show and thus save his own skin a little longer, the Captain engineers simulated moonlight is beamed into the ring and Mags begins to transform into a werewolf.
Unfortunately for the Captain her chosen victim is him – but the whole macabre spectacle has delighted the trio in the crowd. The Doctor and a shaken Mags slip away, with the Family demanding more entertainment. The Ringmaster and Morgana are now tested in the ring and killed when they fail to entertain.
Ace and Dead Beat destroy the Bus Conductor and retrieve the missing jewel for the medallion. With it back in place, Dead Beat’s mind is restored and he becomes Kingpin once more. They return to the circus – disposing of the Chief Clown and his minions en route – to find the Doctor has become the next person in the ring, having responded to a challenge from the Family. When he enters the ring this time he realises that is a dimensional portal and that the Family are in fact the Gods of Ragnarok, who feed on entertainment and kill those who do not satisfy them. After an array of tricks and japes he holds off the Gods long enough for Ace and Kingpin to throw the medallion into the well. It reaches the Doctor through the dimensional portal and he uses it to repulse the power of the Gods. Thus it is they themselves who are the next victims of their own power. The Doctor returns to the Psychic Circus as it disintegrates and explodes, and flees with his friends. He and Ace depart while Kingpin and Mags elect to set up a new circus on another planet.
Doctor Sylvester McCoy (Seventh Doctor)
Companion Sophie Aldred (Ace)
T. P. McKenna — Captain Cook
Jessica Martin — Mags
Ricco Ross — Ringmaster
Ian Reddington — Chief Clown
Peggy Mount — Stallslady
Gian Sammarco — Whizz Kid
Daniel Peacock — Nord
Christopher Guard — Bellboy
Deborah Manship — Morgana
Chris Jury — Deadbeat
Dee Sadler — Flowerchild
Dean Hollingsworth — Bus Conductor
David Ashford — Dad
Janet Hargreaves — Mum
Kathryn Ludlow — Little Girl
Writer Stephen Wyatt
Director Alan Wareing
Script editor Andrew Cartmel
Producer John Nathan-Turner
Executive producer(s) None
Production code 7J
Series Season 25
Length 4 episodes, 25 minutes each
Originally broadcast December 14, 1988–January 4, 1989