Will Ferrell continues to add to his ever-growing resume with a serious turn in director Marc Forster’s light-hearted but thought-provoking “Stranger than Fiction.”

He stars as IRS agent Harold Crick, a shy and timid man whose uneventful life revolves around numbers, order and organization. He even counts his brush strokes when brushing his teeth.

Then one day, out of nowhere, he hears an omnipresent voice speaking to him. Well, not to him, but rather about him — narrating Harold’s every move. The voice is author Kay Eiffel’s (Emma Thompson), who, with the help of her new assistant Penny (Queen Latifah), struggles to write her final masterpiece. The problem for Kay is that she decides she needs to kill off Harold, her main character. But she has writer’s block in figuring out how to do it. She’s unaware the real Harold is directly affected by what she writes, so he must find her before he meets his demise.

Along his way he seeks out the advice of literature professor Jules Hilbert (Dustin Hoffman) to figure out if the story he is inexplicably a part of is either a comedy or a tragedy. Harold also meets Ana Pascal (Maggie Gyllenhaal), a bakery owner who cheats on her taxes. She’s none to happy to have this uptight IRS agent come to audit her, but the two discover an unlikely bond, giving the passive Harold an even bigger reason to stay alive.

Commercials have advertised the film as a romantic comedy, and it does meet those genre requirements. But Forster (“Monster’s Ball”, “Finding Neverland”) and writer Zach Helm have created a story about so much more than the traditional “shy boy meets girl” ritual. In fact, expect some award consideration for the complex screenplay. The story touches on such topics as free will, God, religion, art vs. life, destiny and chance.

Ferrell does a fine job as a borderline comatose depressant who is slowly inspired by these somewhat paranormal events. Hoffman is fantastic as usual as the dry and whimsical Hilbert. The interrogation sequence between he and Ferrell is one of the comedic high points of the film. Thompson is wonderfully touching as the suicidal and aloof author. Gyllenhaal is great as well. Her monologue about cooking is particularly memorable, and the chemistry between her and Ferrell is what drives the movie.

The flaws are few. There are some slow-moving sequences and Queen Latifah’s character is definitely underwritten — a waste of her talent. The ending seems a little negotiated, but then again, so was “Garden State’s.” But it will make you think and will probably provoke all kinds of existentialist dialogue among viewers following the movie.

It’s one of the fall’s best.