Most tales of historical fiction concern characters caught up in sweeping changes in what had been a familiar way of life. Epochal disruptions are typically devastating, life-altering.

But what about characters for whom even gruesome and tragic changes aren't as compelling as their own sociopathic preoccupations? Pablo Larrain's mesmerizing, somehow otherworldly "Post Mortem" explores that question, and is a kind of horror movie on two levels.

One concerns the bloody 1973 military coup in Chile that included the murder of the nation's president, Salvador Allende, and the years-long, monstrous campaign to wipe out thousands of dissidents, intellectuals and other undesirables. The other is writer-director Larrain's unnerving story of a solipsistic oddball very much at the center of events and yet morally sealed within a cocoon of his own making.

Drawing from the actors in his attention-getting 2008 film "Tony Manero," Larrain casts Alfredo Castro as Mario, an eccentric assistant to a hospital coroner. A kind of anti-social variation on Rowan Atkinson's Mr. Bean, Mario doesn't say much but gets around in his little car, fixating on what he wants and freely acting on impulse.

Spying on an equally self-involved neighbor, Nancy (Antonia Zegers), Mario goes out of his way to bring her into his life. The fact that this happens against a backdrop of national turmoil and destruction, of which Mario is only aware insofar as it complicates his personal life and job (which includes paperwork at the morgue where corpses of the assassinated are piling up), is what makes "Post Mortem" fascinating.

If Larrain has a political allegory in mind, perhaps it's simply the way Mario's remoteness is a form of survival in terrible times. "Post Mortem's" dark, dark ending, though, suggests that remoteness might be more: another type of conscience-free tyranny.

Tom Keogh: tomwkeogh@gmail.com