‘Which side is good, which side is bad, and why should I interfere?’ asks the Doctor early in this episode. It’s a good question, and one that reflects the more ambiguous, adult tone of this story. In general, this feels like it has more in common with Whitaker’s The Crusade – where neither the Crusaders nor the Saracens were entirely sympathetic – than the more recent monster serials. It’s a shame, then, that within a few minutes of meeting him Salamander is established as a bad ‘un, threatening blackmail and assassination, and strutting round in his (presumably self-designed) uniform.

Director Barry Letts has cast this really well. Bruce, who could have been an overbearing thug, looks the part of a heavy but has the mind of a policeman, grouching at Jamie to assert some sort of authority having been back-footed by the Doctor and Kent, and slowly unpicking the threads of “Salamander’s” story, and whose appalled reaction to the eruption of the Hungarian volcanoes marks him out as a better man than he seems. As Salamander’s aide Benik, Milton Johns is slightly camp, snide and shady; while as the man of conscience Denes, George Pravda creates a totally credible character from a fairly thin script. And it’s notable to see in addition to Ferrier (who takes all the risks on Kent’s behalf), the similarly-named Fariah, the first significant role for a black woman, is equally strong willed. They all help to sell this as a credible, vaguely Soviet future, where regional commissars plot for power.

Christopher Pemsel’s design work also helps a lot – Salamander’s hi-tech facility at Kanowa contrasts with Denes’ shabby genteel Presidential Palace in Hungary, but even the minor sets, like the disused jetty, work well enough to sell the locations, and give this a tense, Cold War style.

Whitaker gives Troughton a great triple role: as the Doctor he’s gently suspicious of Kent, and (possibly as an ad lib) jumpy about the prospect of a ‘disused Yeti’ which gives the chance for some rare comedy business in a fairly serious episode. Salamander, while clearly a villain, is written with a streak of paranoia and sardonicism that Troughton seizes on, and marks him out as distinct from the Doctor-as-Salamander, who is overbearing without any sense of humour.

Sadly, Whitaker doesn’t put the same thought into Jamie and Victoria’s characterisations: both are written as entirely generic (possibly Whitaker was still picturing Ben and Polly). Jamie is incredibly quick thinking, managing to inveigle his way into Salamander’s confidence through smart talk as much as quick action – not really the stolid 18th Century Highlander we’ve come to know and love. Victoria, meanwhile, gets almost nothing to do bar sit on a bench thinking about food. Somewhere along the line, both author and script editor have forgotten that this is the latest episode of an adventure in space and time, and have reformatted the regulars to suit the plot of the week.

Next episode: The Enemy of the World – Episode 3