The Secret Life of Walter Mitty is a film about a perpetual day-dreamer who is shy and lacks confidence, but he frequently goes into elaborate daydreams about doing cool, exciting and heroic things. One day, a missing photograph that he needs in order to complete the final issue of LIFE magazine spurs him to embark on a global adventure, at which point the cynics in the audience will all start wondering if he’s just dreaming the whole thing.

It seems that Walter (Ben Stiller) himself has similar questions. The third trailer for The Secret Life of Walter Mitty shows him grabbing a sailor’s beardy face in disbelief after jumping out of a helicopter and onto a boat, though this might also be taken as a sign that his grip of reality isn’t completely secure.

If there’s one word to describe the look of The Secret Life of Walter Mitty, “inspirational” would probably do it. The remote locations shown and the crazy adventures that Walter goes on would probably work nicely as an American Airlines commercial, were it not for the fact that Walter seems to travel almost exclusively through unconventional means.

The purpose of the journey is to track down Sean Penn (that should really be the purpose of more journeys), who plays an explorer called Sean O’Connell who represents everything that Walter aspires to be, and who is in possession of the original print for the photograph that is needed. Another of Walter’s main aims in life is to get the girl, who in this instance is played by Kristen Wiig (Bridesmaids).

The reviews for The Secret Life of Walter Mitty have been somewhat mixed so far, with some critics responding well to the heartwarming tone while others call it out for feeling too commercial and phony. It nonetheless looks like a pretty interesting step out of Stiller’s comfort zone as both a director and an actor, and when it comes to Christmas movies, there’s nothing wrong with something that feels little bit Hallmark.

The Secret Life of Walter Mitty is scheduled for release on December 25th, 2013.