Partisans, start your engines.

Journalist Gary Webb’s “Dark Alliance” expose, alleging the CIA played a role in the crack cocaine epidemic of the 1980s, is vigorously debunked in some conservative circles and celebrated by hand-wringing liberals.

Now, a major motion picture is taking sides in the fight. Anyone have a guess as to where “Kill the Messenger” lands?

One’s ability to enjoy “Messenger” hinges on a willingness to take the “based on a true story” label loosely and an appreciation for Jeremy Renner in full indignant mode.

 

Renner plays Webb, a hungry journalist toiling for the San Jose Mercury News. He gets a juicy tip from a drug dealer’s galpal (Paz Vega) that leads him on a whirlwind journey ending with a shocking conclusion.

The CIA knowingly funded the Contras during the 1980s at the expense of urban communities by unleashing crack into America.

It’s all presented in a hurried, linear fashion for time-saving purposes. The real story comes later, when Webb is challenged by both competing newspapers and government officials who’d rather his story not be told. If it must, then it’s time to discredit Webb before too much damage can be done.

“Kill the Messenger” serves as a valentine to take no prisoners journalism, the kind that evaporated as of Jan. 2009. It’s the dawn of the Internet, too, and before the web could crush one newspaper after another it was cool to see your stories available worldwide with just a few clicks.

The movie would have served its audience better with more shades of gray. Instead, we’re treated to scenes like one involving Ray Liotta that add exclamation marks to arguments that nearly everyone agreed weren’t perfect.

It’s time to make Webb a hero, and the screenplay refuses to let anything stand in the way.

The movie skips past some sequences that need more elaboration – was Webb threatened during a meeting with government officials? Did someone stalk his house and allow local cops to try poring over his personal notes?

These moments make that “based on a true story” label feel dicey, in the grand tradition of films taking creative liberties with real events. It’s hard to rally by Webb’s side when his defenders include the Rev. Al Sharpton and Louis Farrakhan, both seen in archival footage.

But is the movie worth watching? Yes, if only for another riveting turn by Renner. His transformation from a chest-thumping journalist to a shattered man trying to hold his family together is ultimately compelling. Rosemarie DeWitt, in what could have been another “wife” role without texture, manages to show how a woman can vacillate between marriage and her own happiness.

“Kill the Messenger” ends up like an Oliver Stone movie without the jump cuts and punk sneer, even if Webb cranks up some Clash mid-movie. Ignore the film’s righteous fury until you do enough homework to find the true story lurking underneath.

DID YOU KNOW: The American Journalism Review’s take on Webb’s story says his editors “failed to hold the story to what he could substantiate, letting him make leaps in reasoning that would earn failing marks in freshman logic.”