When a tube train breaks down and a nurse’s purse is stolen the passengers attempt to find the culprit while they wait for a replacement service. Tensions run high as one passenger refuses to let anyone see what’s inside his bag.

We kick off this final series with what initially seems like a fairly traditional set up for the show –  a group of individuals in a confined space harks back to the very first episode, Sardines, way back in 2014 and most seasons since have included at least one episode with a similar premise. In the hands of lesser writers this kind of drama can devolve into just people arguing but here there is a strong narrative unfolding – you just don’t really notice it until the end.

Reece Shearsmith plays Gerry, the sort of humourless, stick-in-the-mud character he excels at. His wife, Edith (Happy Valley’s Siobahn Finneran), initially seems to be of a similar ilk. Making an outrageous splash is Steve Pemberton as drag performer Wilma (her surname is probably unprintable on a family website!) alongside their belligerent friend Cleo, played by Susan Wokoma (Enola Holmes).

Phillipa Dunne (Motherland) is nurse Elana, the theft of whose purse supplies the main thrust of the plot. Taking unasked charge of the investigation is teacher Raymond, played by familiar TV face and Big Finish regular Mark Bonnar. He very much represents the voice of authority and “reason” and asks the familiar question of if you’ve nothing to hide then why not comply? His initial target for suspicion is a young homeless man (This Country’s star and co-writer Charlie Cooper) who’s been walking the length of the train begging for change. This elicits the usual head-down, say nothing response from most of the passengers although it does spark discussion of the merits or otherwise of an increasingly cashless society. Leading the charge against cards is a young man who refuses to give his name or open his holdall, played by Joel Fry (Our Flag Means Death). He’s very much the polar opposite of Raymond, warning of the dangers of being constantly observed and tracked by cameras and magnetic strips.

Completing the ensemble is puckish old man Harold, played by Matthew Kelly (Stars in their Eyes/Game for a Laugh) who’s more than happy for anyone to see into his carrier bags. You don’t want to know.

Essentially each of these characters represents some aspect of modern society – the knee-jerk anti-authoritarian, the political reactionary, the conspiracy freak, the so-called “sheeple” and so on. It’s an episode that’s a lot more political than usual and is distinctly post-lockdown as it looks at the increasing clampdown on protest and dissent from our current government. I have no idea when this was conceived or written but it does feel very up to date; you can trace a straight line from this to various statements from recent Home Secretaries and Prime Ministers about what we should or shouldn’t agree with and how they, alongside a largely complicit press, portray those with a contrary voice.

As usual with this show things are not quite how they seem (far from it in this case) and the denouement was a genuine surprise to me. Again, as usual, a rewatch sheds a lot of light on it, clues are there and things initially not taken at face value perhaps should be.

An excellent opener and like the best episodes one that will stay with you for a while, it has plenty to think about. The only downside is it may well put you off most Star Wars films for a bit.

Verdict: A lovely, tense mystery with something to say and a spine-chilling conclusion. 9/10

Andy Smith