One of the greatly underrated stories that populate Doctor Who's archives. Why? It's a matter of defying expectations. Of course, now people lap it all up, with Russel T. Davies being congratulated galore for setting up an action-packed adventure about an exploding nuclear power plant, and delivering a soppy moralising sermon against the death sentence. Back, then, however, this behaviour was clearly frowned upon.
This is the second-last part of the mirthful Season 16, remembered for rampant whimsy and a general "Boy's Own" mentality. Furthermore, it is scripted by Robert Holmes, who was famous for his layered, bizarre plots and his sparkling sense of humour. Holmes, however, goes completely against expectations, and delivers a simple plot, filled with gritty violence. Oh, and a big squid.
Kroll, the squid in question, is the most criticised aspect of the entire episode. Holmes famously was asked by script editor Anthony Read to include 'the largest monster ever to appear in Doctor Who', and was relucant to integrate it into his plot. It was definitely a foolish decision, to create such a massive enemy on their often painfully small budget. That said, Kroll's legendary awfulness is much exaggerated. Especially compared to the Skarasen from "Terror of the Zygons"
And, this is all nullified by the skilled dramatic tension Holmes uses in the introduction of Kroll into the story, who is handled by typical horror style, as he is surveyed by the terrified personnel of the rickety refinery.
The plot is very simple. The imperialistic Thawn (the excellent Neil McCarhty) who manages the methane refinery is looking for any excuse to massacre the indigenous Swampies on the moon of Delta Magna. He finds his excuse in the form of a visit by gun-runner Rohm-Dutt to the swampie camp, and aside from attacks by Kroll the plot really doesn't advance much further than that.
What I find appealing about this episode are the gritty portrayals of all the characters. Neil McCarthy's maniacal Thawn is nothing short of brilliant. Phillip Madoc gets less material as second-in-command Fenner, but shows the same flair he had in "The Brain of Morbius". And, finally, John Leeson get to be on camera this episode, and plays Dugeen, the one sympathetic character in the story, and does a very good job. Glyn Owen, likewise, is great as the gruff Rohm-Dutt, even though his character is underused. The rest of the cast all do good work as well.
The episode ends on an exciting note, with a genuinely unexpected Key to Time revelation, and some of Tom Baker's best eccentric behaviour. Interestingly, the episode ends on a different note. No moralising, no judgement of any of the parties. The Doctor just gets the hell out of there! In a way, it shows that imperialism cannot always be fixed.
An episode like this, in my opinion, could only be considered sub-par in a tenure as consistent as Tom Baker's. Nowhere near Holmes' best work, it is true, but mostly because here he writes in another style altogether.