There’s a genuinely impressive amount of world building, references and links to both the TV shows of Torchwood and Doctor Who in Torchwood: One Rule, but even if you’re a more casual fan, this is a great done-in-one adventure that should prove to be an enjoyable listen.

London-based Torchwood agent Yvonne Hartman (Tracy-Ann Oberman) – actually the head of the capital’s Torchwood One – is ambitious, ruthless and willing to do whatever is necessary to ensure that the British Empire is protected from alien invaders.

She’s in Cardiff to covertly acquire a piece of extraterrestrial tech from the city’s Torchwood Three facility – and gets drawn into a series of murders with a political connection, being carried out somewhat anomalously by a mindless alien beast.

This hour long production moves at quite a pace, fitting in a great cast of local characters in its Welsh locale for Hartman to play off of and interact with.

First (and last) spotted in Doctor Who two parter Army of Ghosts/Doomsday, way back in 2006, Hartman is a great character and Oberman slips back into the role wonderfully.

It helps that Joseph Lidster’s excellent script gives her some fantastic scenes, as she reacts to her surroundings and the less worldly characters around her with utter snobbishness, if not always flat out disdain.

She’s a delightfully self-centred character; there’s an awful lot of humour in just knowing how much she hates being forced into this frankly awful situation outside what she would consider the luxury and class of London.

An element of one early killing felt a little bit too much like a ‘bury your gays’ trope, but that minor issue aside, I really enjoyed Torchwood: One Rule.

Fairly unsurprisingly, this did lead to Tracy-Ann Oberman returning to the role of the deliciously bitchy Yvonne Hartman several more times, in Big Finish box sets and one-off dramas; it’s very clear from this one outing, which does a great job of inserting itself into Who/Torchwood continuity, why she became such a popular character.

Not bad for someone who was killed off after featuring in just one story (albeit in two parts) onscreen, right?

Then again, that’s always been one of the major strengths of Big Finish and audio dramas in general; the format allows for an awful lot of leeway in terms of the passage of time, without having to worry about actors appearing much older than they should be during stories – but the freedom afforded by the format also gives writers and producers space to experiment, as well as bring back relatively minor characters to explore them in greater depth.

You can buy Torchwood: One Rule directly from Big Finish here, as a digital download or CD plus digital.

If you prefer, you can buy Torchwood: One Rule from Amazon on CD here.