“I am not leaving my flat!” barks Anthony obstinately early in the film, to the stranger played by Mark Gatiss, who claims to be Anne’s husband Paul. Paul gently tries to explain that he is no longer in his own flat, in fact, but for some time has been a live-in guest in theirs. 

But how can Paul be trusted on this point, when he’s not even reliably Paul? Rufus Sewell is the next actor to arrive, with no explanation, in a more openly malevolent take on the same part. There’s an increasingly taunting edge to these performances, which makes Anthony, in his senile confusion, imagine he’s the victim of some cruel, Pinteresque game.

Zeller’s conceit, so clever it’s hard to suppress a nagging idea it might be *too* clever, is structured to dispense information Anthony doesn’t want to believe and that we can’t take on faith. Reality keeps remoulding itself inside his head, and we’re just onlookers. 

The film does some curious things, detaching itself from any singular point of view and drifting towards the conscience-stricken Anne, who’s fighting a private war with her own resentments. She has a sister we believe to be dead, whom Anthony always preferred, and openly says so: you watch Colman flinch as she absorbs this for the umpteenth time. That bright, make-do-and-mend manner of hers keeps crumpling under the strain – there’s no one more skilful at trying to put a desperately sunny face on emotional devastation.

Nothing in Zeller’s filmic arsenal quite matches the stage potential of the piece, which directors and set designers, not just actors, brought off with a finesse that elevated it to profundity. It’s way more obvious when we sidestep from one location to the next – here’s one style of kitchen, then another. Fluidly handled as they are, the film’s transitions don’t suit the subject quite as well as the many blackouts, like psychic jolts, in Zeller’s stage directions.

From first to last, though, The Father piles justified faith onto Hopkins, whose habitual air of distractability has always made him score especially well as characters under mental siege. He has many good scenes and three extraordinary ones. When a new carer called Laura (a perfect Imogen Poots) is introduced, he turns on the roguish charm but thinks he’s got the better of her, in a devilish double bluff that turns wickedly sour, like one of Lear’s illusory victories. 

Earlier, a characteristic gesture of tugging down one eyebrow – as if to hide his bubbling despair – recalls the great scene in Howards End where he shields his tears from Emma Thompson’s gaze. Childlike vulnerability hasn’t been something Hopkins has opened up to show us in a long, long while, but he seems ready for this role, hungry to do it, and you may not be prepared for how deep he goes. Zeller’s writing, and his shockingly naked acting, peak at the bitter end.

In cinemas now