This had the potential to be an excellent episode but it doesn't quite reach that level. However, it's still a very good one. The Scorpio crew learn that Servalan has hired the assassin Cancer, whom no one alive has ever seen, to kill them and plans to meet him on the rather inhospitable planet Domo. In the hope of killing Servalan before she can do so, Avon allows himself to be captured as a slave. Slavery was established as part of the "Blake's 7" universe in Series One and slaves have made minor appearances on occasion but I think that this is the first time that it plays a major role in an episode. While in captivity, Avon meets and "befriends" (as much as he befriends anyone!) an elderly slave named Nebrox, played by Richard Hurndall whose performance in this episode and (alleged) resemblance to William Hartnell led to him being cast as the First Doctor in the "Doctor Who" story "The Five Doctors". He gives an excellent performance as the sweet natured, downtrodden Nebrox who sadly meets the same fate as the vast majority of sweet natured, downtrodden "Blake's 7" characters. While I don't think that he bears more than a passing resemblance to Hartnell (who was far shorter than he was), his interaction with Piri is reminiscent of the First Doctor's gentler moments with his female companions. I can certainly see why he was cast.
Speaking of Piri, Caroline Holdaway is good at playing the shrieking slave girl but her performance once it is revealed that she is in fact Cancer is horribly over the top. Her poor performance is what kept this from being an excellent episode in my eyes. It would have been nice to have a strong female villain other than Servalan for once. That said, Betty Marsden is very good as the slave trader Verlis and I'd have loved to have seen more of her. John Wynam is also very effective as the faux Cancer. This is really Tarrant's episode and it's nice to see his softer side again. Soolin is once again treated well, given that she is the one that figures out Cancer's true identity. It was also nice to see a major personality clash between Avon and Tarrant for the first time since "Terminal", particularly since their power struggle has gone the way of the dodo.
Speaking of Piri, Caroline Holdaway is good at playing the shrieking slave girl but her performance once it is revealed that she is in fact Cancer is horribly over the top. Her poor performance is what kept this from being an excellent episode in my eyes. It would have been nice to have a strong female villain other than Servalan for once. That said, Betty Marsden is very good as the slave trader Verlis and I'd have loved to have seen more of her. John Wynam is also very effective as the faux Cancer. This is really Tarrant's episode and it's nice to see his softer side again. Soolin is once again treated well, given that she is the one that figures out Cancer's true identity. It was also nice to see a major personality clash between Avon and Tarrant for the first time since "Terminal", particularly since their power struggle has gone the way of the dodo.