The most important aspect of this story is its attempt to examine the nature of crime and rehabilitation versus capital punishment within the context of the series. Its plot trappings are relatively trivial and mainly a means to an end.

Blon Fel-Fotch, the Slitheen masquerading as Margaret Blaine, manages to take over the story, despite having been captured by the Doctor's party, by raising this issue and pushing it to the forefront. Is the death penalty (which she faces on being returned home) a fair punishment for her crimes, or is it a form of legalised murder, which reduces all those complicit in the process to her level (her reply to Mickey's accusation that she deserves it: "And that makes you better than me how, exactly?"). Her asking if any of them would be prepared to do the deed themselves is a point often brought up by opponents of capital punishment, and her challenge for any of the group to look her in the eye (apart from reminding me of the "Look me in the eye...end my life" line used in The Happiness Patrol and Battlefield) is implicitly a means of daring them to prove that they are not squeamish hypocrites.

While posing this dilemma is certainly quite a brave experiment for a series which so often resolves a threat by having it blown up, killed or destroyed in some way (the very next story for example), it's notable that the Doctor remains resolute and unfazed throughout. He is never in any doubt that the correct course of action is to hand Blon over to her species' retribution, and seems unwilling to take any other option seriously. Even though Russell T Davies is on record as opposing capital punishment, and having written this episode to highlight that, it seems very unlikely to me that anyone watching the story would extend that belief to the Doctor. His attitude is clearly that she deserves no better and is too dangerous to be allowed to live. He utters the hand-washing phrase "I don't make the law" at one stage, although given the previous form of this Doctor alone (eg his willingness to allow Cassandra to die in front of him in The End Of The World) it seems unlikely that witnessing her execution would particularly perturb him.

More significantly the story does very little to suggest that he is wrong, and quite a great deal to back up his point of view. Blon's claim to have reformed is plainly insincere, when she has not only been shown to be still murdering her way through any obstacles to her plans at the beginning of the story, but is still trying to make several attempts on the Doctor's life during their restaurant meal (these latter are slightly cartoonish and smack a little of one of Bugs Bunny's and Elmer Fudd's surrealist duels). Furthermore the entire restaurant visit turns out to have been nothing more than a ruse on Blon's part to allow time for her contingency plan to take effect.

Of course, the one exception to this is Blon's sparing the life of a journalist who is threatening to cause trouble, after the latter reveals that she is pregnant. It is as though the mentions of family temporarily depress her due to the reminder of her own bereavement. Apparently feeling unable (for the time being) to visit such an experience an another she lets her go. Yet this fails to impress the Doctor, and his careful analysis of why this is just a token gesture rather than any proof of rejection inspires Blon's accusation that only someone who was as much as a killer as her could understand those thought patterns.

This brings into focus the vigilante nature of heroes. There's no doubt that the Doctor does have a great deal of blood on his hands, considering the various ways he has despatched or defeated enemies of his in the past. So he could indeed be said to have acted the role of executioner before now (what other way could you describe the Armageddon he was apparently forced to unleash to end the Time War, for that matter?). But while there can undoubtedly be an obsessive and ruthless side to the more dedicated justice-seekers of fiction (Sherlock Holmes is a good example), and there is also the old adage about not gazing too long into the abyss lest the abyss gaze back up at you, it can be seen that Blon's and the Doctor's motives and morality are very different. One is acting purely from self-interest and cares not a jot for how many deaths or casualties might result from her plans. The other is, on this occasion, genuinely trying to tidy up a mess leftover from the past, and acting in the hope of saving lives. Killing is a last resort, only to be employed if it means preventing still more deaths, which is how the Doctor justifies Blon's execution (ensuring she will have no further victims).

The story is obviously intended as an analogy over concerns about extraditing criminals to countries where they face execution, which is probably why it tends to shy away from addressing some of the other options available in the fiction. For instance, the Doctor could take Blon to a place and time far removed from the story's setting, where she could never be found, and be too isolated to threaten anyone (he makes an offer along those lines to the Terileptil leader in The Visitation, who is in a similar situation to Blon in some ways). This solution obviously isn't available in the real world, although neither is the one eventually used. Furthermore, giving her a chance to live her life again does beg a question or two. It does seem somewhat unfair or unsatisfying that Blon will get the chance to live again when none of her (many) victims will. That said, it does also help set up the resolution used two episodes later, so could be said to serve that purpose too.

Other than this, the story is notable for progressing the crew dynamics a little further. Mickey is not particularly impressed with Captain Jack on his first meeting, and it's possible to sympathise to some extent with his bored disgust at the self-supportive hand slapping antics of the crew. However, he also demonstrates a greater ability than before in the series to give as good as he gets and seems to quickly settle down into a friendly closeness with the other three. Indeed, the scene where they are laughing and joking together in the cafe is something of a brief highpoint in the characters' interrelations, showing them to be thoroughly relaxed in their own company.

The episode turns out to be quite a strong one for Mickey ultimately, as he gets the chance to round on Rose for taking him for granted so much (which she has done at the very start of the episode, expecting him to come running to Cardiff as soon as she asks), which shocks her into a guilty denial of having intended any slight to him. Her recounting of some of her off-world adventures with the Doctor mean nothing to him, and Rose is still left with some feelings of guilt at the end, while he is prowling the night streets and deliberately keeping out of her sight. The problem, ultimately, is that they have each chosen mutually incompatible ways of living but don't seem willing to fully face the fact that this is bound to alter their relationship. Rose wants to be free to travel with the Doctor as much as she likes, Mickey cannot abide the thought, and yet the two of them remain physically attracted to each other, and Rose's first instinct, when back in her own era, is to call on Mickey for help. Just as, for all his half-hearted attempts to acquire other girlfriends, Mickey still really just wants Rose back. So it's not surprising that she feels somewhat attracted by the prospect of a fresh start herself at the end.

The story is carried to a large extent by Annette Badland's charismatic performance in the role of the main adversary. The script gives her more chance to show off her acting range than her previous story, and she manages to slip between the whimsical "Ooh, silly old me"-style ingeniousness put on for her playacting as Margaret and the cold-eyed vicious snarling of her character's true persona, with apparent ease. The lighting helps too, with one particular shot in the TARDIS lending her expression a decided malevolence. She also carries off the "Teleporting" scene well (one of the better attempts at comic relief in this season).

Although a fairly slight story, it's quite a thoughtful one which turns out to be more interesting than it might seem initially, and deserves some credit as a well-intentioned morality play within the series' format.