Very little of James Thurber survives in Ben Stiller’s adaptation of the writer’s most famous short story “The Secret Life of Walter Mitty,” which was published in The New Yorker in 1939. This new screen version of the tale of the inveterate daydreamer is more Charlie Kaufman than Thurber—hardly a positive change—and the result is even less successful than the 1947 film directed by Norman Z. McLeod: at least that one had Danny Kaye doing his free-wheeling comic shtick as Mitty, while Stiller brings little to the party besides his customary beady-eyed intensity to the character.

And, it must be added, as director he offers a self-help message swaddled in some surrealistically quirky trappings. As reconceived by Steven Conrad, Walter is no longer the henpecked husband escaping from his wife’s nagging into dreams of derring-do; he’s a single schlub who’s signed up to an internet dating site but is afraid to use it. He’s also the longtime chief photographic negative developer at Life Magazine, a job that’s perfect for such a mousy guy but one not long for the world, since the magazine is being taken over by a conglomerate whose hatchet man Ted Hendricks (Adam Scott) is about to convert the whole operation to non-print form. Fortunately Walter enjoys a degree of escape in his elaborate daydreams, in which he takes on heroic personas. That doesn’t come in terribly handy, however, when it comes to approaching Cheryl Melhoff (Kristen Wiig), a fetching co-worker at the magazine with whom he’s trying clumsily to build a rapport.

Walter’s connection with Cheryl receives a nudge when he finds himself suddenly in need of her help to track down famous photographer Sean O’Connell (Sean Penn), who’s sent a slate of negatives to the magazine with the recommendation that one of them be used as the cover of the upcoming final issue. Unfortunately that particular still is nowhere to be found, though most viewers will probably figure out long before Walter does where it is. Anyway, he’s soon off on a real-life adventure to track down O’Connell, with Cheryl helping along the way from home base. The search takes him to Greenland, a disabled ship and ultimately the mountains of Afghanistan before he comes back to New York rejuvenated (or in his case, just juvenated, to coin a term).

The switch from daydreams to real heroics follows the pattern scripters Ken Englund and Everett Freeman fashioned for Kaye’s film, but Conrad’s version—presumably abetted by Stiller—includes more bizarre touches involving an erupting volcano, a helicopter ride with a drunken pilot and a trek to one of the world’s most formidable and dangerous peaks. It also inserts into the story Mitty’s widowed mother (Shirley MacLaine) and overbearing sister (Kathryn Hahn), as well as an oddball turn by Patton Oswald as an eHarmony rep who goes out of his way to serve a customer—a case of product placement beyond the call of duty.

The problem with all of this is that none of it is terribly funny—even a takeoff on “Benjamin Button” comes off more creepy than amusing—especially since by the midpoint of the picture, Mitty’s hallucinations have given way to supposedly real events that are more ludicrous than his early imaginings. There’s some compensation in the sharp, lustrous widescreen cinematography of Stuart Dryburgh and the excellent visual effects work supervised by Guillaume Rocheron (apart from a sequence in which Walter exhibits his skateboarding skill to Cheryl’s son Rich, played by Marcus Antturi, in which the use of a stand-in is ridiculously obvious). And the background score, which melds Theodore Shapiro’s original music with a selection of pop songs, is effective.

In the end, however, Stiller’s take on “The Secret Life of Walter Mitty” fails because it imposes a post-modern, big-budget Hollywood spin on what in Thurber’s hands was a wry little fable of the escapism imagination can afford, and it collapses under the weight of telling us pompously—as Thurber never did—to stop daydreaming and start living our dreams. It’s a movie that, if you remember the three-page original, quickly starts going pocketa-pocketa-queep and never gets fixed.