The first three CDs make sense on their own, as standalone stories, but the final three form a serial, and should be listened to in order. From the early releases, it seemed that the series was telling a story of political intrigue and manipulation that was gearing towards the use of the robot workforce as a means of revolution, as shown previously in "The Robots of Death" and "Corpse Marker". However, the fifth play, "Checkmate" by Alan Stevens, takes the theme of manipulation to a higher level, introducing the Fendahl from Boucher's "Doctor Who" serial "Image of the Fendahl" as the series's major villain, manipulating events in Kaldor City to ensure its own emergence. Once the Fendahl's involvement was made known, it was possible to return to the series's earlier instalments and see the emergence foreshadowed: for example, Uvanov is given a painting of a Fendahleen, and Carnell muses about the existence of an alien grand manipulator whose goals and methods would be unknowable.