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Orac was the thirteenth and final episode of Series A of Blake's 7 first broadcast in 1978. Its cliffhanger; the destruction of the Liberator would be resolved in the first episode of Series B Redemption.


From the VHS release:

Blake and his crew go on a life-saving mission to the planet Aristo, where they must stop Orac, a highly advanced computer, falling into the Federation's hands. But Servalan and Travis have located it too, and Blake is caught in a race against time to save the lives of his crew...


En route to Aristo, Blake reviews the recording of the crash on Cephlon and realises it was caused by a bomb. He also checks the records and finds that Ensor, the scientist who developed the tarial cell used in all Federation computers, disappeared forty years ago with his young son shortly after having an artificial heart fitted. The heart's power cells had a life span of forty years so the cells Ensor's son gave them must be to replace them.

Meanwhile, Jenna and Gan are both feeling ill. Cally runs a scan on Avon and Vila and confirms that all four of them are suffering from radiation sickness as a result of their exposure on Cephlon. Anti-radiation drugs could save them but there are none onboard. Their only hope is to find some on Aristo.

On Aristo, Ensor is informed by a voice he identifies as Orac that a ship has arrived on the planet. Realising they must be hostile since they didn't make contact, he notes the Phibians will take care of them. The new arrivals are Servalan and Travis, who begin making their way through tunnels to Ensor's bunker. Along the way, Servalan is attacked by one of the Phibian creatures and Travis kills it.

The Liberator arrives in orbit. Since Ensor is too weak to give instructions, Orac takes control of Zen and provides them with teleport co-ordinates. Blake and Cally teleport down and are guided through a force field by a probe. They descend to the bunker in a lift and meet Ensor, explaining the situation. They suggest taking him back to the Liberator to fit the power cells but the force field will take too long to disperse and they must travel to the surface. Ensor produces the anti-radiation drugs and also Orac, a box-sized computer capable of tapping into any other computer containing tarial cells and either controlling them or extracting information. Before they can leave, Servalan and Travis attack. The group make it through an escape hatch but are left with a long route to the surface.

Realising Blake has been gone too long, Avon decides to teleport down with Vila. Blake causes the tunnel to collapse behind his group, killing a Phibian, then discovers Ensor has died. He and Cally take Orac to the surface but are confronted again by Servalan and Travis, who took a shorter route. As Travis is about to fire at them, Avon and Vila arrives and Avon blasts him gun arm. Blake leaves the pair behind, saying he'll contact the Federation and tell them they let him get away.

Back on the Liberator, Orac is active and, as a demonstration of his capabilities, shows a prediction of the future. The image is merely of the Liberator flying through space but Orac says the ship will be destroyed. Frustrated at his lack of clear answers, Avon deactivates Orac but Blake says the prediction's still been made. The Liberator explodes.



Story notes[]

  • This was the final episode of Blake's 7's first season and began a tradition of ending a season on a cliffhanger.
  • Travis is played by Stephen Greif for the last time. He was unable to return for filming Series B due to prior commitments and an injury to his Achilles tendon. He was also aware of the repetitious nature of the character. Brian Croucher replaced him.
  • For this episode only, Orac's voice was provided by Derek Farr, who played Ensor.
  • Stephen Greif injured his Achilles tendon whilst playing squash, so was unable to attend the TV Centre studio recordings. Consequently he is doubled in these interior shots, and the camera is carefully framed to avoid showing too much of Travis.
  • Originally, Avon pursued Orac with Cally. It was changed, because it was decided that the thought of Avon meekly handing Orac over to Blake was inconceivable.
  • Blake's "Supplementary to flight log data; vision sweep to line one" utilises 42 seconds of footage from Deliverance. The log is listed as "431, Time Co-Ordinate 662".
  • Terry Nation reused the heroes getting radiation posioning and the search for an antidote plot from Doctor Who's "The Daleks".
  • Avon's line "I was aiming for his head" upon shooting Travis' arm was an homage to The Magnificent Seven. Both Paul Darrow and Chris Boucher were fans of westerns.



Filming locations[]

Springwell Lock Quarry, Ricksmansworth, Buckinghamshire.

Production errors[]

To be added.


  • This is the first episode to feature Orac, who was previously mentioned in Deliverance.
  • A number of extracts from "Deliverance" are used near the beginning of the episode when Blake recaps the events.
  • The plot line of Orac's prediction is concluded in Redemption, although the Liberator would eventually be destroyed in unrelated circumstances in Terminal.
  • Blake refers to Ensor and his son disappearing forty years ago. However, in Deliverance Ensor's son referred to thirty years of independence and in Rescue Avon states Ensor spent the last twenty years of his life in hiding.
  • This is the first episode where Servalan and Travis meet Avon and Vila. (It is also the first time Servalan meets Cally, although Travis previously encountered her in Seek-Locate-Destroy.)


Cally: They've all absorbed heavy doses of radiation.
Vila: Radiation? All of me?

Vila: Die? I can't do that!

Ensor: I disapprove of weapons.
Blake: So do I, but I disapprove of dying even more.

Orac: Modesty would be dishonesty.
Vila: What's wrong with being dishonest?

Blake: Nice shot!
Avon: I was aiming for his head.

Blake: Give us a demonstration.
Orac: Demonstrate as a command is insufficient.
Gan: What does he mean?
Avon: He means, like Zen, that he requires specific instructions.
Orac: Instructions are not needed if commands are succinct.
Villa: I'm getting tired of this.

Home video releases[]

Series 1 DVD

DVD cover

  • In edited form as part of compilation video Orac in 1986.
  • Original BBC video release (Volume 7) in 1991.
  • Fabulous Films video reissue (Volume 7) on 27 July 1998.
  • DVD release as part of the Series 1 box set on 1 March 2004.

External links[]