Released April 2017
SOME SPOILERS FOLLOW

The Fourth Doctor Adventures has long been one of Big Finish’s most conservative ranges, often pitching the stories so that they effortlessly fit into their intended era but sometimes sacrificing novelty and ingenuity in doing so. However, that pattern has slowly been changing over the past couple of years and especially with many of the early releases of this current sixth series. ‘Dethras’ as the latest release not only features an immensely intriguing core concept and setting to bolster its atmospheric and engaging mystery, but it also instills a sense of season seventeen’s lighter stylings into the more grave and earnest season eighteen period.

Upon finding a World War II submarine adrift in space with only three crewmembers and a chimpanzee on board and no explanation for the rest of the missing crew, the Doctor and Romana immediately become entwined in a grand mystery as they try to make sense of the strange goings-on within the ship’s hull as well as of the strange noises coming from outside. The first episode is something of a slower-paced affair understandably more concerned with building up the mystery with compounding confusion, but this approach does at least allow some of the major supporting cast members’ characters to come into focus as they try to come to terms with what they are able to piece together as everything continues to change. Of course, no change is quite so instantly apparent and unexpected as Franklin the chimpanzee’s sudden and progressive ability to speak.

The two-part format’s biggest detriment again rears its head, though, as the second episode must hurriedly rush through plenty of exposition to advance the plot and provide the means for a satisfying resolution to be attained. Though no fault of writer Adrian Poynton, the introduction of the titular Dethras and the Doctor’s recollection of his experiments looking into hyper-evolution becomes a rather wordy affair before the action and the threat of Flague again assert themselves. Still, aside from putting the many odd occurrences into context, the success of Dethras’s experiments brings about a surprisingly poignant reflection on morality and living with the consequences and repercussions of one’s actions. What could have easily devolved into a frivolous story based more on spectacle than substance fortunately turns into a much deeper and more satisfying tale as it progresses.

The guest cast, direction, and sound design bolster a solid script, and Tom Baker and Lalla Ward are on top form as always. Indeed, despite the uneven pacing and somewhat rushed conclusion after some forced exposition, ‘Dethras’ acquits itself quite well and is certainly another strong entry in a range that continues to improve with time. This is certainly not a story that would have been made in the 1970s, especially with the importance of the chimpanzee as events unfold, but the characters of the Doctor and Romana are written and acted so well that they lend a sense of cohesion and stability among a maelstrom of purposeful confusion and experimentation. ‘Dethras’ could have easily been expanded to a more traditional four-part adventure because of all of the nuances in play to better balance out the action and exposition, but it makes the most its running time to create an engaging mystery with a satisfying payoff.