Abiding by South Park’s slogan of attacking everyone to ensure no one’s left on the battlefield to cry foul, Thank You For Smoking is a riotous, caricature-laden satire on dizzying PR spin.

But writer-director Jason Reitman (son of Ivan, who hasn’t made anything this funny in 13 years) doesn’t just fire killshots at paper targets for 90 minutes. A deeply grounded story of a father-son relationship runs tandem with its brightly colored comic exaggeration. (Because any movie in which Dennis Miller still has a successful TV talk show must be fantasy, right?)

It’s based on a very funny source novel by Christopher Buckley, whose buckshot prose has been punched up to include invigorating ideas (surprisingly similar to The Incredibles) and a deeply drawn, fascinatingly flawed protagonist.

Sure, Aaron Eckhart’s Big Tobacco lobbyist Nick Naylor has the same ironsides jaw, waste-eating grin and even haircut that shouts smug as his amoral Chad in In the Company of Men. The difference is that Nick just has a “greater moral flexibility” than most people, and the brilliance in the character is that his virility and vulnerability are equally engaging.

He might be a “sultan of spin,” but Nick’s messily divorced and trying his best to help raise his preteen son, Joey. (Joey might be the first regular kid role for Cameron Bright, used to playing creepy or in-jeopardy youngsters in Birth, Godsend and Running Scared. Nick wants to teach Joey the importance of independent, informed opinion and arguing it when necessary.

Nick likens his own argument to the way Michael Jordan played basketball or Charles Manson killed people. Along with liquor lobbyist Polly Bailey (Maria Bello) and gun-safety spokesman Bobby Jay Bliss (David Koechner), he’s a self-proclaimed “Merchant of Death.” His fast talk is able to twirl even the pending death of a teenage smoker his way in the film’s excellent opening scene.

In doing so, he draws the ire of Ortolan K. Finistirre (William H. Macy), a socks-and-sandals senator from Vermont with a maple syrup collection and deep pride for his state’s cheese products. Finistirre is leading a pack of politicians pushing a bill to place the word “poison” with a skull-and-crossbones emblem on all cigarette packaging.

While Nick verbally spars with Finistirre, he meets with a Hollywood producer (Rob Lowe) to discuss movie-cigarette tie-ins, tries to soothe the anger of a Marlboro Man turned activist (Sam Elliott), tolerates a boss (J.K. Simmons) who steals credit for his ideas, literally falls into bed with a pretty investigative reporter (Katie Holmes) and becomes the target of a violent, anti-smoking group. (Their plot against him and its dripping-with-irony outcome remains stingingly intact.)

Reitman occasionally falls prey to Finistirre’s notion that modern consumers respond better to flashy visuals than meaningful words. Audiences have come to expect zippy graphics and oddly placed subtitles from first-time filmmakers looking for cool points. What they might not is the sharpness of Reitman’s adaptation, given that every performer drops at least one smart-bomb punchline. (In one scene, Lowe gets a belly laugh with a mere downward glance of humility.)

The movie also is careful not to confuse Nick’s good, sensible parenting with big-speech heroics. As important to Nick that his ideas are correct is the vocal rights of those he disagrees with. At the heart of Thank You For Smoking is the idea of believing in your life’s work and excelling through personal responsibility. For that, it’s a comic breath of fresh air.