I would hazard a guess that most people's daydreams don't involve diving head-first into burning buildings or tearing down the street at superhuman speed.

Walter Mitty's do. That said, if Mitty's imagination is stronger than most, his need for escapism is very common. And that is what makes James Thurber's character so appealing. Ben Stiller returns to Thurber's short story more than 40 years after the first film version, starring Danny Kaye, charmed audiences.

While taking full advantage of today's special effects to present Mitty's fantasies, this is a very human story that is sweet and wise, with something to say about the modern world. Stiller, who specialises in meek heroes with something to prove, is well cast as Mitty, presenting him as a good-natured, able fellow, who has simply spent too many years in his shell.

When we first see him, he's tentatively considering whether to "wink" at a colleague, Cheryl (Kristen Wiig), on a dating website. He finds the nerve, only for the website to refuse to perform the function; we assume that for the shy Walter this is par for the course.

On the way to work his imagination compensates for this real-world letdown: he suddenly leaps into a burning building, rescuing Cheryl's three-legged dog and encountering the grateful object of his desire with the pooch in his arms.

This is generally the pattern: when he's humiliated by his boss, Mitty metes out imaginary justice; after Cheryl looks right through him in the office, in his mind he successfully seduces her.

Mitty is a picture editor at LIFE Magazine, which is about to be closed and replaced by an online service (something akin to the real magazine's fate, as it happens).

There is one last issue to produce, and star photographer Sean O'Connell (Sean Penn) has sent a photo for the cover that he claims captures "the quintessence of life". The problem is that Mitty can't find it.

Mitty's search for the elusive photographer and his missing negative represents not only a last-ditch attempt to save his job, but a passage out of his imagination and into the real world. One of the chief pleasures of the film is the way that it presents this transformation.

As Mitty dusts off the passport he's never used and embarks on a journey that will take in Greenland, Iceland and the Afghan Himalayas, we never question that he's up to the task, Stiller avoiding farce for an almost believable travelogue involving an Everyman's fears and growing resolve.

A crucial component of Mitty's maturation is the development of his romantic hopes with Cheryl (nicely played by Wiig). One of the film's best moments is when his fantasy of Cheryl singing Bowie's Space Oddity encourages Mitty to perform a real-life act of derring-do.

The film wouldn't work without an edge, courtesy of the loathsome company man (Adam Scott) brought in to close the magazine and with no feeling for either people or tradition. In contrast, the photographer's "old school" integrity becomes the moral driver of the film.

The iconic Penn is perfect as a man who refuses to take a once-in-a-lifetime shot if he feels that the camera will distract him from living the moment.

Mitty's imagination might well be seen as a metaphor for the world of the internet, social media, smart phones and other tech-driven distractions from real experience.

But the photographer sees something else in him. And when Mitty finally learns what has been captured on the missing negative, the answer is unexpected and quite beautiful, in keeping with the film itself.