DIRECTED BY Shari Springer Berman and Robert Pulcini STARRING Paul Giamatti, Hope Davis, James Urbaniak Opens January 2, Cert-15, 105 mins

OK, so take a deep breath. American Splendor is an underground comic book begun in 1976 by Cleveland native Harvey Pekar. Largely autobiographical, it chronicles the minutiae of Pekar’s life as a lowly hospital filing clerk. It’s funny and sad and helped define comics as a narrative art form beyond the capes and cowls of costumed superheroes.

Along the way, it’s won a ton of awards, while Pekar himself became something of a celebrity, hailed in some quarters as a missing link between Theodore Dreisler and Lenny Bruce and clocking up a number of guest appearances on the David Letterman show. This is a film about Pekar, in which both Pekar himself and an actor playing Pekar (Paul Giamatti) appear. It shares the same metafictional mayhem as Spike Jonze’s Adaptation and the hip geek charm of another great comic book adaptation, Ghost World. You’ll love it.

For those unfamiliar with the glum world of Pekar, American Splendor can initially seem jarring as it hops about from grimy garage sale to shady apartment to anodyne office while Giamatti’s snarling Pekar fulminates bitterly against the idiocies of life around him. But soon, somehow, thanks to the work of co-directors Shari Springer Berman and Robert Pulcini, the movie begins to take on a mesmerising rhythm of its own. For a start, Pekar himself and various other real people (including the scene-stealing Toby “The Nerd” Radloff) are introduced during interstitial Q&A sessions.

The boundaries of comic book and movie start to overlap. Pekar’s rage acquires a level of existential nobility, especially when he’s hit with cancer?he finds himself alone on a blank white page, asking, “Who is Harvey Pekar?”

Though American Splendor has much in common with Dan Clowes’ Ghost World and the work of comic giant Robert Crumb (who illustrated early editions of Splendor and appears here via James Urbaniak’s meticulous performance), it also reveals an affinity with mainstream comics. Here Pekar is the superhero with an iconic outfit of faded jeans and crumpled shirt, and with superpowers of social observation. He springs from one episodic adventure to the next (a nervy first date, a trip to the bakers), and all the while is shadowed by his arch-nemesis, Death. For this is a film that’s bookended by two cancer scares, a film where Pekar consistently frets about his “legacy”, and where his climactic superhero battle takes the form of a woozy chemotherapy montage.

And yet, despite the ostensibly harsh outlook, American Splendor is never bleak. Giamatti helps by adding an eccentric clownish touch to Pekar?the scene where, with voice temporarily lost, he begs his wife not to leave, half-hissing, “Just listen to what I have to say!” is a standout?and the parade of oddball supporting characters certainly raises the quirk quotient. Pekar, too, has an ear for the poetry of everyday speech that’s almost sublime?he remembers waking up alone at night “and feeling a body next to me, like an amputee feels a phantom limb”.

But ultimately the grim reality that Pekar so proudly espouses is bizarrely uplifting because Pekar himself, like a blue-collar Woody Allen, is funny. And when he declares, near the end, that all he’s hoping for is “a window of good health between retiring and dying”, it’s hard not to laugh out loud.