"It's Kind of a Funny Story" is kind of a perfect coming-of-agecomedy, with its bittersweet fun set loose in the adult psych ward of a Brooklyn hospital where this clever case of teenage depression, identity and self-esteem is examined.

But then there's nothing like being surrounded by serious craziness to put your own in perspective, which is exactly what happens to bright, success-obsessed, 16-year-old Craig Gilner, a bundle of complicated charm thanks to Keir Gilchrist ("United States of Tara"). The real revelation though is Zach Galifianakis, best known until now for his turn as the slightly disturbed brother-in-law-to-be in " The Hangover." As Bobby, the psych ward's resident depressive-philosopher, Galifianakis works his character's insights and neuroses like worry beads — effortlessly, unceasingly and to marvelous effect.

We've already come to expect good things from the writing-directing team of Anna Boden and Ryan Fleck, though they've tended to traffic in far heavier emotional fare — character studies like "Half Nelson" in 2006, anchored by Ryan Gosling's standout performance as a teacher in a drug-fueled downward spiral, mixed in with excellent documentary work.

It's nice to see that the filmmakers are equally adept at comedy — setting a brisk pace, balancing light and dark moments, keeping the dialogue crackling and the humor intelligent and indulging in inventive flights of fancy along the way. That's no easy task to pull off, since they're tackling the very real pressure-cooker world of Type A teens who are forever worried that whatever they achieve will never quite be enough (and who, like Craig, often come with at least one Type A parent).

Using Ned Vizzini's popular youth novel as the movie's foundation, the filmmakers have held fast to the book's black comic sensibility but cracked opened Craig's world. Some characters have been bulked up, Bobby most notably, and pretty, troubled teenage cutter Noelle, with Emma Roberts dancing beautifully on a tightrope of appealing and enigmatic.

But above all, Fleck and Boden break the fourth wall brilliantly and frequently, and that inventiveness is one of the film's great charms. Craig moves seamlessly between conversations with us and his hospital stay, when the moments are sometimes real, sometimes imagined and sometimes rendered as complex cityscapes in pen and ink. Cinematographer Andrij Parekh, an indie veteran who has collaborated frequently with Boden and Fleck, does a masterful job of keeping those many worlds turning, giving each a texture all its own.

The story begins in crisis: Craig is considering a suicidal dive off the Brooklyn Bridge, both a boyhood touchstone and a short bike-ride from home — so meaningful and convenient. His is a typical teenage world of extremes, where everything spells devastation and disaster — the cool girl he can't get, the A's he won't make, the colleges he won't get into, the life he won't have and then there is that problem of the projectile vomiting…. Of course, his best friend, Aaron ( Thomas Mann), has won the heart of the cool girl, Nia (Zoë Kravitz), gets the grades without studying, and will no doubt have the vomit-free life Craig longs for. Craig has been in and out of therapy, on and off Zoloft, but coping, like everything else, eludes him.

Instead of a leap off the bridge, though, Craig takes a leap of faith, which is essentially the message of the movie (which thankfully comes with no heavy-handed pronouncements, no ominous music). It is quite simply: Don't be afraid to get help. Indeed, asking for help, the fear someone might find out you got help and actual help become the fast-moving emotional roller coaster that Craig will ride throughout the film.

The story unfolds over the five days that Craig will be held for a basic psychological evaluation — not exactly the quick fix he was looking for when he showed up in the local emergency room. Though the days announce themselves, usually on a black and white title card, time is otherwise a very fluid proposition with counseling sessions, visitors, group activities, meals, chance encounters, phone calls, parents and patients turning up in such a random way that it keeps everyone — on screen and off — a bit unsettled. It's a neat trick that turns the film into an unpredictable grab-bag of funny, tender, ironic, insightful, poignant, hopeful moments that keep surprising you.

The dynamic between Craig and Bobby, where wisdom is exchanged, and the dynamic between Craig and Noelle, where love and trust is the issue, form the heart of the film. But a cast of exceedingly well-drawn characters surrounds them, with a particularly nice turn by Viola Davis as the rock-steady hospital psychiatrist.

Everything moves along to an extensive and appropriately angst-y alt-rock soundtrack as smartly mixed as the rest of the film. Music therapy day comes with a cover of the Queen- David Bowie classic "Under Pressure" that is manic and crazy (in a good way) and captures exactly what being a teenager is all about — kind of like "It's Kind of a Funny Story."

betsy.sharkey@latimes.com