From the VHS release:
At first glance the Federation transmission seems irrelevant. Then Scorpio's crew discover that Servalan is the Utiliser, Cancer is an infallible hired assassin and they are the five subjects...
Onboard Scorpio, Vila intercepts a transmission from Servalan to someone called Cancer, referencing "Domo, the ninth" and "five subjects". Avon is aware of Cancer, a mysterious assassin whose true identity is unknown and who has never failed an assignment. The crew guess that they are the five targets and decide to go on the offensive: Domo is a planet and it seems likely Servalan is meeting Cancer there on the ninth.
Avon and Vila teleport down to the surface and Vila watches from a distance as Avon approaches a group of pirates led by Benos, who deal in slaves. Posing as a crash survivor, Avon allows himself to be taken prisoner but the plan goes wrong when his teleport bracelet is confiscated. Avon is imprisoned with another subject for the slave auction, Nebrox, who confirms Servalan is on the planet. She bought one of a group of entertainers who was then sent to a black ship, evidently Cancer's, that left shortly beforehand.
At the slave auction, the auctioneer, Verlis, allows Servalan to bid on Avon. Nebrox manages to get the teleport bracelet back off Benos: In return, Avon has Dayna teleport down with a spare bracelet and gun. In the melee that follows, Avon kills Benos before he, Dayna and Nebrox teleport up to Scorpio. The crew set off after Cancer's ship and find it drifting. Avon and Tarrant teleport aboard and make for the control room. They fire at the figure in the pilot's seat but it is merely a dummy. The black-clad Cancer emerges from hiding, gun raised, but is attacked by a young woman named Piri, allowing Avon and Tarrant to overpower him. Piri explains she was bought by Servalan to help Cancer "celebrate".
The crew decide that Vila and Dayna will take Scorpio out of range, while Avon, Tarrant and Soolin remain on Cancer's ship, with Cancer as a prisoner, to set a trap for Servalan when she makes contact. Nebrox and Piri also decide to remain on the ship. However, when Cancer gets free, Avon decides that instead of searching for him on his own territory, they will take the ship back to Xenon so Cancer will be forced to either surrender or remain in hiding until he starves. This goes wrong too when the engines go dead.
Things worsen when Nebrox is killed and the air supply is cut. Avon, Tarrant and Soolin lock Piri in the relative safety of the cargo hold and split up to search the ship. Soolin sits down to puzzle things out and someone places a robot crab nearby. Just as it is about to attack her, she stands up, unaware of the danger. Meanwhile, Avon is knocked out and recovers to find himself being held prisoner by a black-clad Piri: She is Cancer. The man they encountered was the entertainer Servalan bought, hired to take part in the subterfuge, who she has now killed. Servalan has been monitoring events throughout and controlling the ship by remote.
Cancer recalls the robot crab, which injects its subject with venom and which she used to kill Nebrox and the fake Cancer. She turns it on Avon but Soolin has also worked out the truth and she and Tarrant arrive. Soolin knocks the crab off Avon onto Cancer and it injects her with venom, killing her. With Servalan having left the radio channel open during her gloating, the trio send an emergency transmission to Scorpio. Servalan has her ship intercept and destroy Cancer's ship but unknown to her Avon, Tarrant and Soolin are already safely back aboard Scorpio.
- Avon - Paul Darrow
- Vila - Michael Keating
- Dayna - Josette Simon
- Tarrant - Steven Pacey
- Soolin - Glynis Barber
- Slave/Orac - Peter Tuddenham
- Servalan - Jacqueline Pearce
- Verlis - Betty Marsden
- Nebrox - Richard Hurndall
- Piri - Caroline Holdaway
- Cancer - John Wyman
- Benos - Peter Attard
- Tok - Adam Blackwood
- Servalan's Captain - Mark Barratt
- Stunt Co-ordinator - Terry Forrestal
- Production Manager - Rosemary Crowson
- Production Associate - Frank Pendlebury
- Production Assistant - Joan Marine
- Assistant Floor Manager - Christopher Moss
- Film Cameraman - Fintan Sheehan
- Film Sound - Stuart Moser
- Film Editor - Sheila S. Tomlinson
- Videotape Editor - Malcolm Banthorpe
- Visual Effects Designer - Jim Francis, Mike Kelt
- Video Effects - Robin Lobb
- Graphic Designer - Dick Bailey
- Properties Buyer - Francis Smith
- Technical Manager - Jack Walsh
- Senior Cameraman - Dave White
- Vision Mixer - Nigel Finnis
- Studio Lighting - Brian Clemett
- Studio Sound - Richard Partridge
- Special Sound - Elizabeth Parker
- Costume Designer - Nicholas Rocker
- Make Up Artist - Suzanne Jansen
- Music By - Dudley Simpson
- Series Created By - Terry Nation
- Although Slave is visible on Scorpio's command deck, he has no dialogue, so Peter Tuddenham was only required to voice Orac.
- The season 4 blooper reel features a couple of scenes between Servalan and Verlis which were cut from the broadcast episode.
Sandpit, Bovington Camp, Dorset.
To be added.
- Cancer knows Servalan as Sleer, the alias she has been using since Traitor. However, Avon uses her real name when talking to her over the communicator, possibly suggesting her crew are aware of who she is.
- How Piri found the time to get her hair and makeup done in time for her reveal as the real Cancer is not adequately explained.
- At the end of the episode, Servalan believes Avon and Tarrant to be dead, stating that a universe without them will take some getting used to. Despite this, she shows no surprise when Belkov mentions them as being alive in the following episode, Games.
Avon: You know how much it hurts me to use the word infallible.
Tarrant: Oh, come on, nobody's infallible.
Avon: All right, then, he's not infallible. It's just that up till now he's never failed.
Vila: You're gonna kill an unarmed prisoner?
Soolin: When did you get religion?
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.