The Last King of Scotland may never play in rural Nebraska, but the Rural Nebraska Film Critics Society might say Forest Whitaker gave 2006’s best male-lead performance on precedent.

Practically every other critical group has rewarded him, and he’s considered a shoo-in for an Oscar. Whitaker’s much-ballyhooed performance as madman Ugandan ruler Idi Amin isn’t worth the greatest-of-all-time hyperbole. But one scene proves just how transcendent his acting is above what becomes an otherwise rote on-the-run thriller that sidelines Whitaker in its second hour.

Amin wakes in the middle of the night with severe stomach pains. Convinced he’s been poisoned in an assassination attempt, he calls for his personal physician, Nicholas Garrigan (James McAvoy), to treat him immediately. Garrigan grabs a baseball bat after spotting open bottles of beer and pills, asks Amin to sit down, presses the bat to his stomach and has him stand up.

What emits is a subwoofer-rattling fart that would make a sound-effects guy on a kids’ film weep, and that it’s only trapped gas is nominally funny for about a second. But Whitaker twists the throwaway gag into deep character nuances of Amin’s recklessness, paranoia and shame at showing weakness. That is how good Whitaker is; it’s not just the wheels of evil that turn in Amin’s brain, but also how the mentally claustrophobic mix of fear and power can cause rot and decay.

On that front, Whitaker and Scotland get right what Sean Penn and All the King’s Men got wrong. Whitaker’s organic work towers over the rest of the movie, as it takes an almost-Boogie Nights approach to the African-plight trend. It’s drenched in a funky soundtrack and (perhaps correctly) equates Amin’s opulence with a rock ‘n’ roll lifestyle.

But shifting focus to Garrigan, his awfully dumb decisions and his attempts to escape Amin’s fast-closing grip feel like Dirk Diggler enmeshed in intrigue that’s political, not pornographic.

In an awards-consideration sense, the dirty little secret is that it’s really McAvoy’s movie and Garrigan’s story — a hedonistic Scottish doctor yearning to break free from his family’s expectations by spinning the globe and going to the first place he stops and points. OK, the second place, forgoing Canada for Uganda, where he quickly beds a local woman charmed by his exoticness. (McAvoy is good enough, blending Ewan McGregor’s gangly Scottish sexuality with a face and attitude of Russell Crowe, 20 years younger and scrubbed for prep school.)

Garrigan’s eyes are traumatized by sickness and death at his initial post at a rural mission, so it’s no wonder they glaze over at the pageantry of presentations from Amin. He’s recently overthrown the government in a British-sponsored coup and promises prosperity to this independent African nation. Director Kevin MacDonald (Touching the Void) wisely cuts to Amin’s gesticulating hands during political rallies, as he’s a spider that uses them to help invite so many flies to his parlor.

When Amin sprains his hand in a traffic accident with a runaway bull, he’s impressed both by Garrigan’s passer-by diagnosis and the way Garrigan grabs Amin’s gun to mercy-kill the animal. An invitation to become Amin’s personal physician follows, and Garrigan accepts like a fawning college recruit. In time, Garrigan learns that Amin’s gregarious good guy attitude actually is a front for being a monster in human form — a creature Garrigan crosses personally once he becomes involved with Amin’s beautiful third wife Kay (Kerry Washington), in a telegraphed plot point.

MacDonald and cinematographer Anthony Dod Mantle’s African drama is sultrier and sweatier, but no less beautiful-looking, than its recent brethren. That slickness keeps Scotland watchable even as it turns into a messier version of The Constant Gardener’s suspenseful moments awash with nervy, percussive music. Two torture moments are the only things you won’t see coming.

It’s a good thing Whitaker takes center stage again in the finale, showing the full blood of a character that can quickly flip charm and wit into a nightmarishly bipolar mentality. His performance is an unpredictable force that proves unstoppable in not letting the rest of the film fail.