Doctor Who: Devil in the Mist

The TARDIS arrives on an alien spaceship transporting a war criminal with telepathic powers to his prison. Soon enough, things start going wrong, and everyone is trying to survive on a hostile planet. That's the basic plot, anyway, and it moves along at a good pace, with plenty of changes of scenery as things develop. But it's not the plot that's likely the main selling point here.

Instead, that's the first appearance of Kamelion in a Big Finish story (in fact, the first of a trilogy featuring the character). Kamelion appears in only two TV stories, and for much of those is under the control of the villain, so that we never really get to see him as a companion. Arguably, of all the characters who appear on official lists of TV companions, only Katarina is more obscure. Here he's played by impressionist Jon Culshaw, something made easier by the fact that most of the time he's in robot form and speaking with an electronic voice.

Naturally, Kamelion has a key part to play in the story, which is connected (of course) to the villain's telepathic powers. We perhaps don't get much insight into the character here, although it's debatable how complex he's supposed to be, since he may not be programmed with much personality of his own. More significant is Tegan's distrust of him, something that we saw in The King's Demons, but that was never worked out on screen when technical issues curtailed Kamelion's role on the show.

In fact, Tegan is key to the plot. The Doctor is partially incapacitated for much of it, and, while not exactly sidelined, passes much of his usual active role to his companions, with Tegan being the more prominent of the three. For much of this time she's forced to interact with the potentially untrustworthy robot and this drives a significant element of the story. There are also a number of twists and turns along the way, as different concerns come to the fore and it turns out that not everything going on with the aliens is quite what it seems.

A good, fun story that fairly zips along. With a shape-changing robot and space hippos.