The painfully silly conspiracy thriller “A Dark Truth” comes in two basic settings: It’s either whisper-whisper-mumble as the characters drone their way through an endless series of dull conversations or BAM-KA-BLAM as everyone shoots their way through pedestrian action scenes that wouldn’t be out of place in a direct-to-DVD cheapie.

Had this movie gone straight to video without passing Go and without collecting (possibly a literal) $200, we could ignore it. But no, it’s on the big screen (and on demand), with a cast that includes Forest Whitaker, Eva Longoria and Andy Garcia, so attention must be paid. Even if such attention is barely earned.

We begin in Ecuador, where villagers are running for their lives through the jungle with trigger-happy soldiers in hot pursuit. It’s a sequence that lets us know that revolutionary leader Francisco Francis (Whitaker) and his wife Mia (Longoria) have witnessed something horrible, and it also tells us that writer-director Damian Lee has almost no idea how to shoot an action sequence.

Young Ecuadorian Renaldo (Devon Bostick, of the “Wimpy Kid” franchise) manages to escape thanks to his ties to CIA agent Tony (Steven Bauer); we next see Renaldo in Toronto, where he blows his brains out in front of philanthropist and water-filtration company exec Morgan (Deborah Kara Unger) to protest what her company did in his village.

Turns out, the filtration system wasn’t ready for the river to overflow and for the sewage system to back up, which led to a horrible typhus outbreak. Morgan’s brother Bruce (Kim Coates) then got the local military to come in and kill everyone to cover up the disaster, since he’s got a pending deal to build a huge water system in South Africa. Bruce tries to assure Morgan that nothing is amiss, but she hires CIA-agent-turned-talk-radio-host Jack (Garcia) to go to South America and check things out. (His show bears the unpretentious title “The Truth,” incidentally.)

This sets up lots more mumble-mumble (whether it’s Garcia talking to Whitaker about the will of the people or water-company no-goodniks conspiring in a series of blue-lit rooms) and bang-bang, but none of it registers. There are certainly points to be made about corporate exploitation of the third world -- and the opportunities of making those points probably attracted name actors to the project -- but any and all ideas are lost in the jumble of this tedious, flat movie.

Longoria goes full-on Serious Actress here, from wearing minimal amounts of makeup to trying to sell dialogue like, “How long can anyone live? The answer is always the same: Until we die.” It’s a noble effort, but one better suited for a smarter movie. Garcia and Whitaker look pained and earnest, as though every scene were a late-night commercial for a child-hunger charity, and the usually compelling Unger seems incapable of emotion or expression here.

(The best performances come from Bostick and Bauer who are, alas, dispatched all too early.)

By the time we get to the shootouts in downtown Toronto and the gruesome comeuppance to the bad guys, “A Dark Truth” has forfeited any opportunities it has either to entertain or to inform. Its good intentions accomplish nothing but additional paving of the ever-lengthening path to Movie Hell.