So, well, Prisoner is stupid. It’s fun. But cor – is it stupid. By which I mean that if the new six-part action thriller about a prisoner and his escorting guard being handcuffed together and on the run was a person, you’d think – cor, they’re stupid, but unchallenging and pleasant enough company. Maybe I’ll stick around. Maybe I won’t. You would think something very much along those lines.

The Prisoner setup is simple. We first meet the prison guard, Amber (Izuka Hoyle, too good for the material but she is young, up and coming and there will be no harm done) as she says goodbye to her baby, leaves him with stay-at-home dad Olly (Finn Bennett, who’s been in some good stuff and should try that again) and rejoins her prison guarding team after six months’ maternity leave.

She, as you totally would not do on your first day back after six months’ on maternity leave, volunteers for an extra job that comes in for overtime. She and a colleague are sent to pick up a special prisoner who needs transporting overnight from an isolated hideaway to the Old Bailey. To make it absolutely clear that something is going to go very wrong, she puts a family snap on the van’s windscreen shade thingy.

Meanwhile, we the viewers are learning – repeatedly – from a large group of men in white shirts and one woman, whose entire character description probably read “Hardbitten divorcee. Takes no prisoners” and no one even noticed the pun, least of all the writer. The men are led by Alex (played, inexplicably, by respected actor Eddie Marsan) and the woman, Josephine (played, equally inexplicably by equally respected actor Catherine McCormack), is their boss. Together they are the national Crime Unit and have devoted the last seven years of crime uniting to bringing down the head of the Pegasus Crime Syndicate, Harrison Dempsey (Brían F O’Byrne), a commanding, convincing presence amid the rising chaos.

His trial – on charges of being a total baddie – has begun. Its success hinges, as I understand the trials of criminal conglomerate bosses always do, entirely on the testimony of one man and one man alone: Tibor Stone (Tahar Rahim). He was a prolific contract killer for Dempsey (“47 confirmed kills,” says Alex. “And those are just the ones we know about.” “Wait,” says I. “Do you mean, there are other confirmed kills you don’t know about? In which case, what is your definition of ‘confirmed’ here? Have you just said the same thing twice? Don’t you tell me not to be pedantic! You write proper instead! Tcch!”). He also has Type 3 diabetes, which is the kind where you need an insulin shot every time more jeopardy is required.

This, of course, is the man Amber currently has in the back of her van, the van with the family snap stuck on the windscreen thing, and, oh, criminy, what’s this? An ambush, you say? While the men of the NCU are busy still repeating to the viewer that if Stone doesn’t get there, Dempsey will go free and their investigation will have been for nothing? Nothing! Wait, I still don’t get it, can you repeat that? Oh, you are. You know, I was actually joking. Never mind. The ambush is under way.

Kapow! Boom! Shooty-shooty! Van overturned! Armed escort of the escort are outmanned and outgunned (there’s a whole 3D printer weaponry warehouse thing happening elsewhere). Amber scrambles to release the prisoner from his van-cage and handcuffs them together to stop him absconding. Oh Amber, you noble fool! A splinter of Tilda Swinton whom we will come to know as Nina (Leonie Benesch) is on their trail and stays on it for much of the rest of the time.

From there it is an ever-growing mass of set action pieces, insulin shots under increasingly unlikely circumstances, an arrogant Dempsey heir running interference, wounds patched without anaesthetic, Amber being required to question how far she will compromise her ethics to protect a bad man (and who IS a bad man anyway? Getting deep, man), suspected moles in the NCU (“This is going to cost you everything!”) and an unusually high ratio of weak performances unable to make the best of an already bad script. But it looks slick, and who has the energy to care all the time about characters or sense or why a man would run over the panes of a glass roof instead of the joists in between or anything at all, large or small? It’s an action movie that’s managed to compress the basics – see “Kapow! Boom!” above – but not cram in the details. It’s two and a half stars but the half fell into one of the plot holes and cannot be saved.