In last year’s lucrative yet scattershot documentary Won’t You Be My Neighbor?, the world of the much-loved children’s TV staple Mister Rogers was gently cracked open for an audience who might be familiar with his on-screen persona but less aware of his personal life. There were no major insights but even the smallest detail proved illuminating, rounding out and reaffirming the image of a rare public figure defined by genuine, untarnished goodness.

Anyone hoping for dirt in Marielle Heller’s semi-true semi-biopic A Beautiful Day in the Neighborhood will leave unfulfilled, rather like the film’s actual protagonist, the cynical, mostly fictional journalist Lloyd Vogel (Matthew Rhys). Loosely based on the writer Tom Junod, who was sent to interview Fred Rogers for Esquire in the late 90s, Vogel sees the assignment as a step down, a puff piece handed to someone who should be dealing with the harder stuff. He arrives at the Mister Rogers’ Neighborhood studio with a chip on his shoulder and, after meeting the man himself (Tom Hanks), remains unconvinced yet intrigued. He can’t quite believe that Rogers’ amiable and selfless on-screen persona is real, partly because of his usual investigative mode and partly because he was abandoned by his father (a pitch perfect Chris Cooper) at an impressionable age.

As we enter another turgid biopic season, it’s always a pleasure to encounter one that chooses to opt out of the traditional formula. Technically, this isn’t really a biopic at all since Rogers isn’t the true protagonist and the film only focuses on a brief, half-fabricated period of time, leaving much of his life unexplored. It’s more of a father-son story featuring an unlikely added element, a man who can’t resist inserting himself into the lives of others – especially those in need of help. Once you get past the loose handling of the truth, there’s a warm hug waiting for you in A Beautiful Day in the Neighborhood, and one that arrives with far less sentimentality than expected. Rogers always respected his audience, no matter the age, and Heller follows suit, avoiding the sugary overkill so many other directors would have embraced.

It’s a remarkable three for three now for Heller after her unvarnished teen drama The Diary of a Teenage Girl and last year’s melancholic masterpiece Can You Ever Forgive Me? With her biggest film to date, she confirms that she’s the real deal, confidently showcasing her adeptness with a larger canvas while also infusing her film with an idiosyncratic touch. There are many smart flourishes, from her subtle recreation of late 90s America (as evocative as Can You Ever Forgive Me?’s early 90s New York), to the seamless inclusion of Hanks in pre-existing footage, to the decision to replace location shots with toy cityscapes, something that could have seemed cutesy but, in the world Heller creates, feels quite perfect. She’s able to conjure a mood that runs through the mostly straightforward narrative, a deceptively simple skill that many directors with far greater experience cannot master.

A deep-rooted transformation: Tom Hanks as Fred Rogers. Photograph: Lacey Terrell

Casting Hanks as Rogers seemed almost too fitting conceptually – one beloved, fundamentally “good” US father figure playing another – but their charms are vastly different. Rogers had a calming stillness to him while Hanks has a more lively, boyish effervescence. Heller has spoken about a process of essentially deprogramming Hanks, forcing his regular tics to fade away. It’s a deep-rooted transformation and, while Hanks avoids attempting to awkwardly replicate Rogers’ voice – although he does nail his cadence – he focuses on exuding the same bewitching, patient curiosity that Rogers had in the people he met.

It’s a given that Hanks will nab at least a best supporting actor nomination but it would be all too easy to forget his co-star. The cynic-becomes-a-believer arc is age old but it unfolds here without cliche thanks to an emotionally intelligent script from Noah Harpster and Micah Fitzerman-Blue, but mainly because of a marvelous, prickly turn from Rhys, who post-The Americans and now this deserves more substantial roles.

It’s not a film without fault, with one over-egged dream sequence falling flat and some last-act emotion not hitting quite as hard as it should, but its warmth radiates throughout. Many people will surely herald this as the film we “need” right now but that’s a meaningless statement and what’s important about the lessons of acceptance and forgiveness that Rogers preaches is that they’re lessons we need at any time and likely always will.