Transformers: The Last Knight review: Michael Bay's latest escapade doesn't even try to make sense

The Last Knight, dear friends, is the fifth Transformers movie, and we need not detain ourselves too long with the nonsense which has preceded it. Shia LaBoeuf starred in the original 2007 film as Sam Witcicky, an annoyingly perky American teenager who discovers that his car is really a shape-shifting robotic alien, or Autobot. The Autobots are good, the Decepticons not so much, and Sam ended up joining forces with the Autobots' leader Optimus Prime to prevent the Decepticons from destroying our planet.

They saved the planet again in the summer of 2009, yet again in 2011, but when LaBouef's box office cachet collapsed spectacularly thereafter, director Michael Bay decided to replace him with the more reliable Mark Wahlberg for the 2014 outing, Transformers: Age of Extinction. It's all very tiresome of course, but no matter, because to date the franchise has grossed almost $4bn, and while Michael Bay has insisted this will be the last of the Transformers films, I'm not entirely sure I believe him.

Outlawed after an unseemly row that decimated much of downtown Chicago, the Autobots have been forced into hiding, and are protected by inventor Cade Yeager (Wahlberg). They've made their stand in a Dakota scrapyard, but several interested parties are about to sniff them out.

The Decepticons and their deranged leader Megatron, who's a kind of tin-sided Pol Pot, are out to get Cade, but so is a volatile robot servant called Cogman (voiced by Jim Carter, the butler guy from Downton Abbey), who persuades Cade to fly to England to meet his master.

Sir Edmond Burton (Anthony Hopkins) tells Cade that Transformers have been on Earth for a very long time, and played a key role in the Arthurian legends. A staff given to Merlin by an Autobot has lain beneath the English Channel for centuries, but now a Cybertronian sorceress called Quintessa is looking for it, helped by an apparently hypnotised Optimus Prime.

If she finds it, it will be curtains for everyone, and only Cade and an under-dressed English Literature professor called Viviane (Laura Haddock) can stop her.

That plot sounds a bit convoluted, doesn't it, and Michael Bay takes his own sweet time expounding it. If Bay ever read Hamlet, he missed the bit where Polonius tells a bored-looking Claudius that "brevity is the soul of wit". All the other Transformers films are long, but this one clocks in at a positively exhausting 149 minutes. Is there any need?

The problem with these films has always been the fact that they fatally lack charm. No matter how silly a voice you give them, the Transformers themselves are impossible to engage with, and Optimus Prime, who's supposedly the most interesting one, is so pompous he'd give old Polonius a run for his money.

I must admit I was mildly engaged by a spectacular Arthurian prologue in which a drunken Merlin (Stanley Tucci) saves his king from certain defeat after being given that weaponised staff by a robot alien. But the central plot is a priceless bore, and the Decepticons are hopeless villains - they've had five good chances to destroy this blessed planet, and it looks like we're going to have to finish the job for them.

Anthony Hopkins hams it up outrageously as usual as the stuffy English nobleman, but cannot be blamed for failing to take this muck seriously and provides moments of actual entertainment. That quality is otherwise in short supply in a film that outstays its welcome by around 148 minutes.

Transformers: The Last Knight (12A, 149mins) ★★

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Also out this week:

Films coming soon...

Despicable Me 3 (Steve Carell, Kristen Wiig, Steve Coogan); Baby Driver (Kevin Spacey, Ansel Elgort, Jon Hamm, Jamie Foxx); Halal Daddy (Colm Meaney, Deirdre O'Kane); The House (Will Ferrell, Amy Poehler, Jeremy Renner); Risk (Julian Assange).