"Automatic reaction, I'm as surprised as you are."
Cally, under the control of an alien being, sabotages the Liberator forcing it into a largely uncharted star system and into a web like structure in space which mobilises the ship. The Alien force takes control of Jenna and summons Blake to their planet. Cally believes they are lost members of her race the Auron. They attempt to escape the web by firing Liberator's neutron blasters but fail in their escape attempt. Blake teleports to the planet where he encounters the diminutive Decimas who attack him before he find shelter in a structure containing a paid of humanoids who introduce themselves as Novara & Greela. They are running out of power and want Blake to provide charged energy cells. The Liberator detects approaching Federation pursuit ships. Novara & Greela tells Blake that the Decimas, and themselves are genetic creations of another being who he is introduced: Saymon a small deformed being living in a tank, the combined form of the 6 Auron who came to the planet. Avon teleports to the planet with the power cells. They are taken into the compound by Novara & Greela, but the Decimas attack killing Novara & Greela. Avon & Blake install the power cells which causes the web to disperse and teleport to the Liberator as the Decimas kill Saymon. The Liberator evades the pursuit ships and escapes resuming it's course for Centero.
Or "an alien force possesses one of the crew forcing the ship off course but our heroes defeat them". So there was Jenna worrying about bringing Cally on board in the previous episode and straight away Cally does something odd and puts them in danger!!!!!!! Deary me. This is the first episode of the series not to be on one of the compilation video tapes put out in the 80s and you can see why: it's not essential to the ongoing storyline of putting the crew together or Blake vs the Federation. I look at it and just see bits ripped off from here there and everywhere. It doesn't help that every time Novara (Miles Fothergill) speaks all I can hear is his more famous role as SV7 in Doctor Who's The Robots of Death (Director: M Briant). Adding to the knock off feel of the episodes are the Decimas who look quite a lot like grey shrunken Zygons.
The Liberator uses it's weapons for the first time in this episode to try to disperse the web. We also get to see for the first time the closest thing Blake's Seven ever gets to a Uniform as the hooded outdoor gear makes it's début. Blake is wearing green, Avon grey/dark blue. Over the next few episodes everyone gets a set in their own colours..... until SOMEONE chooses a completely different style and stands out from the others.
Playing Auron gestalt Saymon is Richard Beale who's got some Doctor Who experience. He was a Refusian Voice in the Ark, Bat Masterson in the Gunfighters, the Broadcaster in Macra Terror and Minister of Ecology in The Green Death (Who directed that .... oh yes: Michael Briant!). He'll later appear in Tripods series 2 as Ulf in episodes 2 & 3 of the second series. Ania Marson playing Geela has 5 episodes of Target to her name. Playing the Decimas are a number of actors of diminutive stature who are known to us from various other locations. Top of the list is Deep Roy with Mr Sin in DW: The Talons of Weng Chiang to his name. He returns for several more Blake's 7 episodes: B11 Gambit as The Klute, C11 Moloch as the voice of Moloch and C13 Terminal as a Link. He's best known today for being all the Oompa Loompas in the most recent Charlie & the Chocolate Factory. Marcus Powell will shortly get an uncredited appearance in Destiny of the Daleks to his name as well as returning in C4 Dawn of the Gods as The Thaarn. His extensive CV includes time as one of the original Oompa Loompas, as was another Decima Ismet Hassam, Time Bandits as Horseflesh, The Tripods as cook in the 3rd episode of the first series and in Star Wars cantina as Rycar Ryjerd cantina where he met his partner Gilda Cohen who is also a Decima in this episode.
Rather sadly I rumbled where this episode was filmed while watching it: Black Park in Buckinghamshire, which backs onto Pinewood studios and has thus been used in many films! Doctor Who went there for Full Circle and it was used in 5 UFO episodes (including the first Identified) and 3 Space 1999 episodes, including The Full Circle.
This episode of Blake's 7 was broadcast 2 days after Doctor Who episode 473 Underworld Part Four, which was broadcast on 28/01/1978, and 5 days before episode 474 The Invasion of Time Part One, which was broadcast on 04/02/1978.
This is the first of the series not on one of the 1980s compilation tape so the first time I saw it was when it was released on Monday 7th Jan 1991 paired with the following episode Seek-Locate-Destroy as Tape 3 and alongside the rest of the first 8 episodes all paired off The Way Tape 1 Back/Space Fall, Tape 2 Cygnus Alpha/Time Squad & Tape 4 Mission to Destiny/Duel with a DVD release for the whole of season 1 happening on 01/03/2004.