From the VHS release:
The implant in Gan's brain was designed to limit aggressive impulses, but when it malfunctions he is in urgent need of neuro-surgery. But will the doctors at Space Research Station XK72 aid a wanted criminal?
Gan is alone on the Liberator flight deck when he begins experiencing head pains. Jenna arrives and manages to bring the ship back under control but then Gan attacks her. He is only subdued when Blake and the other crewmembers arrive. An examination of the unconscious Gan in the medical bay confirms what they all feared: Gan's limiter is malfunctioning.
Blake and Jenna check possible locations where they could find a surgeon to treat Gan but Avon reveals an option that Zen has left off the list: XK72, a neutral research station. Zen states that heading to XK72 in the time specified would require traversing a zone he has been programmed never to travel through and refuses to set the course. The crew head off manually but once they enter the zone Zen shuts down. Since the ship relies on computer control, the only option is for Avon to bypass Zen.
Gan manages to trick Cally and attacks her, then also attacks Avon before collapsing. Avon manages to bring the computers online and the crew discover the threat Zen predicted: A gravity whirlpool. Blake takes the Liberator through the centre of it and they emerge intact.
Once at XK72, Blake teleports aboard and meets with administrator Farren and chief surgeon Professor Kayn, posing as the captain of an experimental Federation ship. Kayn agrees to return to the Liberator with him. Avon heads over with a teleport bracelet for Kayn's assistant Renor but remains on the station himself to talk with Farren. His latest brush with death has caused him to reconsider his position aboard the Liberator and he offers teleport technology in return for being allowed to stay on the station and a promise not to inform the Federation of the Liberator's presence.
Alone with Renor, Kayn reveals he has already deduced the identity of Blake and the others. He delays the operation and instructs XK72 to alert the Federation. Farren is furious when he finds out and informs Avon, suggesting he stay on the station so if the Liberator is destroyed or escapes the Federation will think he was onboard. Avon returns to the Liberator, supposedly for his things, but informs the crew of the situation. Vila has already becomes suspicious of Kayn, holding him at gunpoint, and Blake forces him to perform the operation before teleporting him and Renor back to XK72.
A group of Federation ships attack the Liberator. Kayn tries to instruct XK72's arnaments to join the battle. Farren intercedes and Kayn kills him. A Federation plasma bolt misses the Liberator and strike XK72, destroying the station. The Liberator evades pursuit and the crew gather around a recovered Gan.
- Blake - Gareth Thomas
- Jenna - Sally Knyvette
- Avon - Paul Darrow
- Cally - Jan Chappell
- Vila - Michael Keating
- Gan - David Jackson
- Zen - Peter Tuddenham
- Kayn - Julian Glover
- Farren - Ian Thompson
- Renor - Christian Roberts
- Stunt Co-ordinator - Peter Brayham
- Production Assistant - Geoffrey Manton
- Production Unit Manager - Sheelagh Rees
- Film Cameraman - Ken Willicombe
- Film Recordist - John Gatland
- Film Editor - M.A.C. Adams
- Series Videotape Editors - Sam Upton (Uncredited), Malcolm Banthorpe (Uncredited)
- Visual Effects Designer - Ian Scoones, Mat Irvine
- Electronic Effects - A.J. Mitchell
- Graphics Designer - Bob Blagden
- Studio Lighting - Brian Clemett
- Studio Sound - Clive Gifford
- Special Sound - Richard Yeoman-Clark
- Costume Designer - Rupert Jarvis
- Make Up Artist - Marianne Ford
- Music By - Dudley Simpson
- Series Devised By - Terry Nation
- Working title: Brain Storm.[source needed]
- The episode was a heavily rewritten version of an earlier script called The Invaders.[source needed] The first half was largely unchanged but the original script had the Liberator travelling through a fluid cloud (similar to the one later seen in Terminal) and a lifeform that only Gan can see coming aboard the ship. The lifeform ended up taking on Gan's form and Blake and Gan teamed up to force it into the teleport chamber and teleport it off the ship. The visit to the station formed a much smaller part of the narrative, with the staff merely performing the operation and giving the Liberator time to get away before informing the Federation.
TV Film Studios, Ealing.
When Avon teleports to XK72, he is shown to take only one bracelet and then sends the surgical assistant back to Liberator, which would require Avon to have given him his bracelet. However later, when Avon learns of the Federation pursuit ships on their way, he has a bracelet with him.
- The crew considers taking Gan to Kainnessos, Overon, Cassiona and Epinal for treatment of his limiter.
- Gan's limiter was established in Time Squad.
Jenna: They don't like humanoids in general and particularly Homo Sapiens.
Avon: That puts their intelligence beyond doubt.
Blake: Presumably Zen will come back to us when we're out of danger.
Vila: Sounds like a good idea. Any chance of joining him?
Avon: In the unlikely event we survive this...
Avon: I'm finished. Staying with you requires a degree of stupidity of which I no longer feel capable.
Blake: Now you're just being modest.
Home video releases
- Original BBC video release (Volume 5) in 1991.
- Fabulous Films video reissue (Volume 5) on 26 May 1998.
- DVD release as part of the Series 1 box set on 1 March 2004.