The title, "A Separation," is an apt encapsulation of the film as a whole: It may sound simple, but its results are devastating.

Writer-director Asghar Farhadi's tale begins life as a domestic disagreement in contemporary Iran and morphs into a legal thriller, one that will have you questioning the characters -- and your own perception of them -- again and again. This transformation occurs intimately, organically, and seemingly so effortlessly that you may not recognize it right before your eyes. But the lasting effect will linger; while this story is incredibly detailed in the specificity of its setting, its themes resonate universally.

Farhadi sets the tense tone right off the top with a long, single take in which middle-class husband and wife Simin (Leila Hatami) and Nader (Peyman Moadi) sit before a judge to explain their dispute. She wants the family to leave Tehran to provide their studious daughter, Termeh (the director's daughter, Sarina Farhadi), with better educational opportunities. He wants to stay and care for his aging father, who's suffering from Alzheimer's. And so Simin is asking for a divorce. When that request is rejected, she moves out and returns to her parents' home; while the daughter stays, Nader still needs help watching his father, who tends to stray and needs assistance with basic daily functions.

Nader hires a young, devout Muslim wife and mother named Razieh (Sareh Bayat) to serve as housekeeper and caretaker while he's at work and Termeh is at school. He thinks he has everything back under control. But one fateful decision leads to another, and then another and another, until finally, serious criminal charges are at stake. The situation explodes with the introduction of Razieh's volatile husband into the mix (Shahab Hosseini, who may be a bit too over the top), a man who's as steadfastly protective of his wife as he is unstable emotionally.

"A Separation" honestly addresses the notions of trust and respect, loyalty and religious devotion. And while it revisits a pivotal moment with hints of "Rashomon"-style shifts in perspective, it has a structure and narrative style that's confidently its own. Who knew what about whom, and when, is crucial -- and here's a friendly suggestion to pay attention, because these essential nuggets of information may slip past you, as well, upon initial viewing.

Farhadi lets resentments simmer naturally, lets scenes escalate on their own without overhyping the melodrama with needlessly overwrought music and the like. Similarly, he never takes sides, which means we can't either -- which sucks us in further. Each time we may think we understand someone's motivations, more information is revealed which forces us to re-evaluate the character as well as his or her place within this increasingly complicated scenario.

You could easily imagine this sort of dispute erupting and bursting out of control. And the fact that the naturalistic performances are, for the most part, so precisely calibrated makes "A Separation" even more believable and engrossing.

Movies with this kind of moral complexity are rare, so not only is it worth seeking out, it's one you need to see with friends because it invites -- or rather demands -- debate afterward.

Three and a half stars out of four.