From the VHS release:
A killer robot, the final creation of Ensor's prize pupil Muller, is on the rampage in the base. Intent on total control of the universe, it needs Orac to fulfil its destiny...
Tarrant and Vila are en route to the planet Pharos aboard Scorpio to collect Muller, a scientist who has agreed to join them. Muller's lady, Vena, is already on Xenon Base. Tarrant teleports down to Muller's laboratory where Muller shows the half-hidden body of a man who tried to stop him. A technician enters and Tarrant knocks him out. Tarrant teleports Muller up to Scorpio, then grabs a box and follows him. Muller is horrified and attacks Tarrant. Vila strikes Muller with a wrench, accidentally killing him. Back on Pharos, the technician investigates the body and reports that he thinks Muller is dead but isn't sure: The head is missing.
Vila and Tarrant put Muller in stasis in the hope they can revive him back on Xenon. However, Orac instructs Avon not to let anyone leave Scorpio. Avon orders the ship, which has already experienced a number of problems including Slave refusing to obey orders, to stay in orbit in quarantine. However, when life support fails and Orac is unable to provide a reason to maintain the quarantine, Avon sends Dayna and Soolin up to retrieve the crew.
Dayna teleports Avon and Vena up to Scorpio to find Muller while Soolin treats Vila and Tarrant. Orac tells Soolin the human race will be wiped out unless she conceals him so she complies. Avon and Vena find the stasis chamber empty, while someone teleports down and overpowers Dayna. Avon and Vena return to Xenon and meet with Vila, Tarrant and Dayna; Avon suspects Muller is alive and insane. Muller appears and, when Vena goes to embrace him, he crushes her to death. Avon and Tarrant aim their guns at him but the circuits fail and the crew retreat.
Realising Muller can control circuits, Avon sends Tarrant and Dayna to get a percussion grenade from the armoury. The explosion apparently kills Muller but then he rises from the rubber minus his head: He is an android. Avon, Vila and Soolin discover the box contains a robot head. They realise the truth: The head was meant to restrict the android's behaviour but it killed Muller before it could be fitted, using his head to pose as him. With its circuit power and Orac's ability to access information, the android could dominate humanity.
Having temporarily sealed the android in sickbay, Avon comes up with a plan to disable it with an electric charge and fit the head: A nearby hydro-electric plant would be immune to the android's control. Vila and Soolin decoy the android with Orac, who is already falling under the android's influence, while Tarrant and Dayna operate the power plant and Avon rigs up cables to a bridge.
Vila and Soolin join Avon and the android is electrocuted crossing the bridge. Avon fits the head but is knocked out by an electric shock. Tarrant has him carried clear and, without telling the others, he and Dayna set up explosives that destroy the android. Avon is furious at the loss of the technology, despite Orac stating it was the only way for humanity to be safe.
- Avon - Paul Darrow
- Vila - Michael Keating
- Dayna - Josette Simon
- Tarrant - Steven Pacey
- Soolin - Glynis Barber
- Slave/Orac - Peter Tuddenham
- Muller - John Westbrook
- Vena - Lynda Bellingham
- Technician - Douglas Fielding
- Android - Nick Joseph
- Voice - Lesley Nunnerley
- Production Manager - Ralph Wilton
- Production Associate - Frank Pendlebury
- Production Assistant - Valerie Turner
- Assistant Floor Manager - Josephine Ward
- Film Cameraman - Fintan Sheehan
- Film Sound - John Tellick
- Film Editor - Sheila S. Tomlinson
- Videotape Editor - Sam Upton
- Visual Effects Designer - Jim Francis, Andy Lazell
- Video Effects - Robin Lobb
- Graphic Designer - Dick Bailey
- Properties Buyer - Francis Smith
- Technical Manager - Terry Brett
- Senior Cameraman - Dave White
- Vision Mixer - Mary Kellehar
- Studio Lighting - Warwick Fielding
- Studio Sound - Malcolm Johnson
- Special Sound - Elizabeth Parker
- Costume Designer - Nicholas Rocker
- Make Up Artist - Suzanne Jansen
- Music By - Dudley Simpson
- Series Created By - Terry Nation
- This was the last of three episodes written by Roger Parkes.
Box Hill, Surrey
To be added.
- This is one of only two episodes where the crew are seen outside the base on Xenon, the other being Power.
- Ensor is mentioned.
Vila: A little hard work never hurt anyone.
Tarrant: How would you know?
Orac: We can fulfil your every desire.
Soolin: You wouldn't know where to start.
Avon: It's superstitious halfwits like you that hold back every advance we make!
Orac: And arrogance, Avon, like yours and Muller's, which threatened to destroy...
Home video releases
- Original BBC video release (Volume 23) in 1992.
- Fabulous Films video reissue (Volume 23) on 6 September 1999.
- DVD release as part of the Series 4 box set on 24 April 2006.