This story could be described as a culmination of the increasingly harsh universe of the Davison era, as already witnessed in the likes of Earthshock, Warriors and Resurrection, where no-one can be guaranteed to get out alive, and with an ever more blurred line between who the goodies and baddies really are. It's also a portent of the unabashed cynicism of the forthcoming Colin Baker era, with its fetishes for sadism, amorality and genetic alteration.

The Doctor and Peri are seriously out of their depth here, almost as soon as they stroll innocently into the fray - really, as soon as they have both been unknowingly infected by the raw Spectrox. Both are caught up in a world governed by little more than ruthless self interest. Chellak and the army are prepared to execute them for the sake of expediency, even when the former begins to doubt their guilt of gun running. He is also persuaded by the android Salateen to send ensign Cass on a deep penetration mission (from which "very few return") - in effect, to have a soldier killed so as to get rid of any potentially awkward witnesses to his having executed two androids by mistake. Hence even Chellak's apparently straightforward dedication to duty, which would seemingly make him the most sympathetic or heroic supporting character, has a nasty and merciless edge.

It is arguably Morgus who really sums up the spirit of the world the story takes place in though - well, he and the gun running party. We soon learn, from observing his activities on Androzani Major, that Morgus is the very worst kind of businessman, exalting profits for himself at the expense of any kind of public good. Essentially, if it gets him money, anything goes. Murder (the deaths caused by the Porthcawl mines sabotage, to say nothing of the war he is sponsoring, or the use his guns will be put to), slavery (his proposal to have the unemployed put in labour camps) and personal treachery (as attested by Sharaz Jek) are all quite legitimate methods to him. He puts up little shows of morality (his asking Timmin to arrange half minute silences for deaths he secretly caused) for appearance's sake, but these are all uttered in a spirit of cold calculation. When the Doctor turns up unaccountably alive in Episode Three, Morgus's instincts are that offering him as much money as possible will get him what he wants.

Furthermore we are also shown that the system he operates in is corrupt enough to tolerate at least some of the cruelty and ruthlessness he advocates. The President's "Yes, we might make that seem morally justifiable" to Morgus's proposal about the labour camps indicates an intention to do the indefensible while putting a false gloss on it. Forms and appearances are all that matter, providing they conceal the ugliness beneath effectively enough.

Nevertheless, the fright Morgus feels when he thinks the Government has discovered his gun running role, his panicky murder of the President and his fleeing to Androzani Minor, all help to show that he is sitting on a potential Time Bomb throughout the height of his apparent political influence. Timmin's smug gloating at him in the final episode when he has been reduced to the status of an outlaw, and it becomes clear that she has known of his illegal activities all along but simply being biding her time for the right moment, is not only a richly satisfying turnabout in his fortunes in the story, it also shows that his position has actually been extremely delicate from the beginning. In the end he is no less of a common criminal than Stotz, "just a man with a gun" as the latter observes, for all the would-be prestige his position as a descendant of the first colonists holds. Not, of course, that this stops Morgus from considering himself entitled to lord it over others. His disgusted "You cowardly curs!" to Krelper may be partly frustration but likely also reflects his need to have creatures he can look down on.

Stotz himself has already murdered the survivors from his crew, as well as nearly finishing Krelper off earlier with the poison capsule (and as a writer once suggested, that scene was probably meant to be an inversion of the scene where the Doctor saves Peri's life by giving her some of the Spectrox cure), so there's no doubt about his murderously competitive nature. By the time Morgus and Stotz are prowling through the misty caves at the end, you tend to feel it's largely a question of which one will kill the other first, especially given the argument they have about how the Spectrox is going to be shared out. The intention is unspoken, but the way they look at each other makes clear how far each will go to protect their cut.

Sharaz Jek is probably the most interesting and vividly drawn character though. Seemingly a cackling black-clad baddie, he ultimately turns out to be probably the most sympathetic and sensitive of them. He still has dreams of a better world to keep him going, and probably genuinely wishes, on some level, that he could really settle down comfortably with Peri in an idyllic and peaceful world. He cares about beauty and the arts, and is clearly still in mourning for his old self, when he was "comely". The fact that he feels forced to live this fugitive subterranean existence while trying to blackmail Major into giving him Morgus probably sharpens his loathing and resentment all the more. His opinions on Stotz and the others ("These petty criminals are invariably paranoid, their twisted little minds infested with distrust and suspicion...to think that I, who once mixed with the highest in the land, are now dependent on the very dregs of society...the base, perverted scum who contaminate everything they touch!") express all the yearning he has to be free of his current grim situation and regain what he thinks Morgus has taken from him.

Hence I don't think his obsession with Peri is primarily lustful, I think it is a case of her youthful beauty symbolising everything he wants and believes in but which he assumes is now denied to him. He wants to express affection, to have someone attractive to lavish devotion on, and I find his eventual death - collapsing into the arms of his Salateen android, who remains loyal and faithful to him throughout - one of the most moving in the Dr Who stories.

The production values are a bit variable, with some rather cheap looking backdrops in Morgus's offices, and some extremely basic sets and low-fi technology on display. Admittedly, though, the latter are probably partly intentional, to show deprived and on the edge conditions on Androzani Minor are. The story is also helped by some extremely assured and fluent direction which manages to retain and build up a sense of rising tension and desperation throughout the last two episodes in particular. There's also good use made of montages of shots fading into each other (e.g. Jek building his androids of the two regulars), as well as the occasional practice of slow fades between scenes instead of direct cuts. The lighting is also commendably dark and dingy.

Nicola Bryant is pushed into a mostly passive role again, as she has to spend much of the story growing progressively ill and helpless. Peri ultimately becomes the means of the Fifth Doctor's redemption, with his struggle to save her life eventually triumphing at the expense of his own. He has failed to save Adric, he has had to adopt distasteful methods in his lifetime, he has had to witness and cause many deaths on different occasions, but here he is able to focus on rescuing and curing his one companion above anything else, even preserving his life. The story is the Fifth Doctor's redemption, seen most symbolically perhaps in his last desperate rush to the TARDIS in the wilderness, Peri cradled in his arms.

Peter Davison delivers one of his best performances in the role, managing the flippant teasing with Jek, as well as the obsessive urgency of his need to save Peri later in the story. He's arguably never more the innocent caught up in a cruel world than here ("I am telling the truth, I keep telling the truth! Why is it no-one believes me?"), and the character triumphs ultimately even in death, having been ultimately the only one in the story to have acted entirely out of altruism and compassion with no base or selfish instinct at all. Whereas in Resurrection he is never really in a position to make good his claim that he does "not accept" the "universal way of life" involving warfare and killing that Davros describes, here he does manage to emphatically deny it by his own unselfish actions, which do generate a positive result. His values have won a sort of victory, with Peri's life having been saved, in comparison with the self-destructive nothingness that has resulted on Androzani Minor.