Our window into this doesn’t even have a name.

What he does have is Alzheimer’s, and all that it brings. The film’s opening sequence captures his son, Nader, sitting with wife Simin. She has come for a divorce. In Iran, both parties must agree before such a dissolution can be granted. The camera takes the perspective of an unseen judge, before whom the couple – not for the last time – are called to defend themselves. Simin pleads with the camera to be allowed to leave the country; ‘the situation’ isn’t good for their young daughter, she sobs. Nader looks resigned, saying only that he must stay behind to look after his ailing father.

Finding themselves at such an impasse, Simin goes to stay with family while her husband is left to care for their daughter, Tehmeh. Nader arranges for a carer to come in and help with his father while he is at work. The woman is from one of the poorer, more religious areas of the country, and seems unbearably anxious even before she has begun. On her first day, Razieh finds the elderly man soiled, staring vacantly at the floor. Offering a towel does no good, since it is apparent washing is now utterly beyond him. Overcome with guilt, she phones a religious scholar and wonders whether it is more of a sin to clean this man than to leave him as he is.

The politics and strange customs of religion are but one theme in a rich tapestry. This is not an especially polemic film, which is perhaps just as well. Asghar Farhadi has instead made a more universal picture, tempering its controversies with a story that centres on domestic estrangement. When Razieh reluctantly returns to the house the following day, she does so without the knowledge or consent of her husband, which becomes important consideration when a violent argument lands her in hospital. The authority this time is a local police chief, who presides with ever-decreasing patience over a case that sees Nader facing jail and Razieh struggling to keep her threadbare story from coming apart.

Amongst the recriminations and counterarguments, we return time and again to Termeh and her grandfather. Alzheimer’s is a uniquely dehumanising sentence which seems to render its victims as leaden-props to be moved into position. He is without words, yet his observance of the house speaks loudly in their absence. Save for his son, those around him often treat his care as little more than an afterthought, with directions to ‘keep watch’ often ignored to the point of cruel sport. Such flippancy leads to situations most helpless; the elderly man wedged behind a door someplace or, just once, tied to a bedpost while his carer runs errands. When he subsequently falls face first onto the floor, he must remain there until his son arrives home early from work.

Termeh, on the other hand, has words and uses them judiciously. She remains a quiet and well-mannered child, who grows suspicious of her father’s story. She, too, is an authority figure of sorts, yet A Separation is not her judgemental account, nor anyone elses. No one acts unreasonably, as if motivated by the whims of drama. We understand their choices and are able to sympathise with them in a way that defeats so many other films. It would have been easy in the circumstances – perhaps not unfairly – to paint Nader as the villain of the piece, just as Simin could well have been a beaten-down, eastern stereotype: the eternally sorrowful wife, refused her freedom by a callous husband and the justice system that enables him.

Neither is the case, and A Separation is especially involving for that. There are no easy solutions to be found, cultural or otherwise, yet this Iranian drama remains inescapably contemporary, whatever the larger theatre.