A heady blend of deadpan farce, precise ethnography and quasi- biblical allegory, this small and absorbing Icelandic film is much more affecting than its modest ambitions may seem to promise, a small masterpiece in a minor key.
The rams of the title belong to the flocks of brothers Kristinn (Juliusson) and Gudmund (Sigurjonsson) - respectively known as Kiddi and Gummi - neighbours in an isolated valley in rural Iceland.
For reasons that emerge slowly, they haven't spoken to each other for 40 years, although their enmity is obvious from the first scene in which a farmer's instinct trumps fraternal ill-feeling - but only just.
They are rams too, the title suggests, fruitlessly headbutting each other in an endless rivalry whose roots go deep.
Director Hakonarson, who wrote the delicately modulated screenplay, is alive to the situation's potential for absurdist comedy - the dog that carries written messages when communication cannot be avoided is one of several lovely touches.
Likewise, the bitterness that erupts when one brother's ram is judged the winner of the annual competition has a petulant childish edge, but soon we realise that the reaction is a curdled blend of deep hurt and family pride.
But when an outbreak of scrapie hits the flock, condemning all the sheep in the region to slaughter, we see economic uncertainty at work, and before long, the brothers' conflict will reach a tipping point.
Cinematographer Sturla Brandth Grovlen, who shot last year's dazzling one-take heist thriller, Victoria, captures the wide, white locations and grimy cramped interiors with a fidelity that gives the film the feel of a documentary.
The effortlessness with which the film keeps all these aspects in play is deeply impressive.
At the same time, and without a trace of self-consciousness or heavy-handedness, Hakonarson taps into something almost mythical: the bearded brothers, who could have stepped off the set of an Old Testament epic, may hate each other, but they share a fierce pride in their flocks' pure and ancient bloodline.
This, he seems to suggest, is a story as old as Cain and Abel.
Theodor Juliusson, Sigurdur Sigurjonsson Director: Grimur Hakonarson
M (offensive language, and nudity.) In Icelandic with English subtitles
A small masterpiece in a minor key