The marketing people behind this new film want you to believe that this is a Tom Hanks/Sandra Bullock film; even the poster has the pair as equal top billing. And it's true that they do appear in it, but the truth is that the real star of the film is the extremely young and incredibly talented Thomas Horn.

You probably haven't heard of him before, as he makes his acting debut in this film. He did make a name for himself some other way however. Question: Who won $31,800 on the US quiz show Jeopardy! during Kids Week? Answer: Thomas Horn.

Legend has it that the film's producer Scott Rudin was so impressed with the youngster, that his appearance on the show led to him being auditioned for the main role of Oskar.

And clearly a kid this smart wasn't going to be phased by such a thing as an audition. At this rate he'll either be the President of the US whilst still being in his teens, or the sharpest real-life Bond villain the world has ever known. As you would expect, he wins either way. But after watching his performance, it would be difficult to deny him either.

There's something quite different about eleven year-old Oskar Schell (Horn); he's special in every which way. Because his behaviour was considered so unlike that of all the other kids, he was tested for Asperger's. Turns out that he really is just special. He has an enquiring mind, but it comes at a price; the world is full of fearful things that make getting around and talking to people around him kind of tricky.

His rock in this weird world of his is his dad Thomas (Hanks); by profession he may only be a mere jeweller, but he stimulates his young son's mind like no one else can.

And then 9/11 happened and Oskar's rock was gone forever. Oscar doesn't cope well with this loss. It takes him a year to venture into his father's closet, where many of his curious nick-knacks are kept. In an attempt to reach his father's camera on the top shelf, a blue vase falls to the ground and breaks. Amongst the broken pieces Oskar discovers an envelope with the word 'Black' written on the outside. And inside is a plain key.

Thomas was certainly one to set his son challenges whilst he was alive, so Oskar naturally believes that these two clues form part of the very last challenge from his father. With only a word and a key to go on, Oskar begins his most challenging adventure yet.

Don't look at me like that Max, I thought you loved pastrami on rye?!

Even though, without labouring the point, this film has appearances from both Hanks and Bullock (as Oskar's mother), it wholly relies on the performance of its young debutant. It's a tall ask too when you consider he appears in virtually every frame of its two-hour plus duration. Horn however, is a phenomenal revelation.

His staggering performance belies his years. He supplies such emotional gravitas into the role that it feels almost impossible that someone so young – and beginning their acting journey to boot – could deliver such a mesmerising feat. It would be no surprise to learn, some years down the line, that they actually discovered a way of squeezing Dustin Hoffman inside a state-of-the-art latex outfit to play the part. This has to be the only reason why Horn doesn't find himself amongst the Best Actor nominations for this year's Oscars, because he truly deserves to be there.

He gets a little support from those around him however; the scenes he shares with Hanks, however short, are painfully touching and clearly explain Oskar's need to still maintain some kind of relationship with him, ever after his death. And then there's Max von Sydow (who does, quite rightly, get an Oscar nod in the Best Supporting Actor category), who gives a sublime performance as the mute Renter. And what initially feels like a perfunctory role of the mother by Bullock, suddenly develops into something with more meaning by the film's end.

There's a subtle subtext regarding the tragedy of 9/11, but the real crux of the story concerns a young boy dealing with the loss of his father. The fact is Hanks' character could have died in a fishing accident and it would still hold as much of an impact emotionally. Using 9/11 however certainly amplifies the intensity of sentiment.

It could have been easy for emotions to ride a little too high throughout, but director Stephen Daldry (Billy Elliot, The Reader) acts as an earth, preventing the film from becoming a movie-of-the-week weepy in free-fall, as he translates Jonathan Safran Foer's book beautifully to the screen.

With his skill, he helps produce a truly bittersweet experience that reminds you just how much of an impact one film can have. So much so that if you're not wiping the tracks of tears from you face (be it openly or surreptitiously) at some point, you must consider yourself thoroughly broken.

Extremely Loud & Incredibly Close is a poignant, moving and tender celebration of the fact that a love lost doesn't mean that it also dies.