Andrew Haigh’s All of Us Strangers is an aching tale of grief, loss and loneliness starring Andrew Scott and Paul Mescal, so I probably don’t need to tell you the acting is off the scale but I will anyway: the acting is off the scale. Scott, in particular, infuses his character with such vulnerability that you’ll want to reach into the screen and comfort him. And while it does feature ghosts, don’t let that put you off. They’re the doable kind rather than the walking-through-walls, ‘wooOOO-wooOOO’ kind. (Huge relief all round.)

Haigh makes complex, intimate, single-protagonist films (Weekend, 45 Years, Lean on Pete) and this is no exception. Here Scott plays Adam, who lives on the 27th floor of a plush but barely populated London tower block that gives off Ballardian vibes. The opening five minutes do enough to tell us he is not in a good place. He watches daytime TV, eats biscuits, inspects the contents of his fridge (curdled takeaway leftovers), puts Frankie Goes to Hollywood’s ‘The Power of Love’ on the turntable, which becomes something of a leitmotif.

He is a screenwriter and has written the first line of a script – ‘EXT. SUBURBAN HOUSE. 1987’ – but that’s it, he can’t get any further. He is prompted to dig out a box of old family photographs which in turn prompts him to visit his childhood home near Croydon where, astonishingly, he finds it’s still 1987 and his mother (Claire Foy) and father (Jamie Bell) are somehow alive. They died in a car crash when Adam was 11 and are the age they were then, which means they are slightly younger than their adult son.

Adam is overwhelmed and elated, whereas they are welcoming but behave quite normally. He might have just returned from popping to the corner shop for a Marathon that’s yet to become a Snickers. They are amazed to discover what he does for a living. ‘A writer, our son,’ says his mother. His father puts his hand on his but quickly retracts it. ‘Enough of this poofy stuff,’ he says. Adam is gay and never had the chance to come out to them. Based (very) loosely on the novel Strangers by Taichi Yamada, the film is about the conversations with parents that were never had and the acceptance that was never received.

Adam visits his parents over and over – taking a deep pleasure in it even if it becomes more complicated and tense over time – while another story is unfolding back at the tower block. There seems to be only one other occupant, Harry (Mescal), on the sixth floor. Emboldened by whiskey, Harry comes knocking at Adam’s door one night, seeking company, but Adam won’t let him in. Not letting people in is what Adam does. (This is a subtle film that is occasionally not that subtle.) They eventually embark on an intense – and hot – romance. Can Adam, finally, succumb to ‘The Power of Love’?

The film is mesmerising and deeply affecting (I cried) with many stand-out scenes. Foy and Bell bring a strange, eerie, everydayness to their roles; Mescal remains sexy even while drunkenly desperate. As for Scott, the only other actor who is capable of conveying so much sadness and sensitivity beneath the surface is, possibly, Ben Whishaw. Not everything is spelled out, particularly the ending, which may make you sit up and say: ‘Hang on, what?’ But here’s a tip: clock what Harry is wearing the first time we meet him and what he’s wearing in the final scene. This is key.

Could you call it a ghost story? Probably, but these are the sort of ghosts we can get on board with.