Here is a most unusual comic drama from Iceland that plays some very clever games with tone. For much of its duration, Grímur Hákonarson's Rams – winner of Un Certain Regard at Cannes – deals in the sort of dry quirk we have come to expect from Nordic cinema. As events progress, however, the picture imperceptibly softens into something much more poignant.

Gummi (Sigurður Sigurjónsson) and Kiddi (Theodór Júlíusson), two elderly, sheep-farming brothers, live only a few hundred yards from each other, but they almost never speak. When communication proves unavoidable, a smart, charming dog carries messages from one grump to his equally unyielding neighbour.

We begin with the annual competition for best ram in the area. Kiddi’s sheep just takes the prize and Gummi is sent into an unreasonable rage. When Gummi suggests that his brother’s animal may have “scrapie” (BSE), the neighbours not unreasonably accuse him of sour grapes, but, sure enough, the infection is confirmed and the authorities order a cull.

It is perhaps sentimental to suggest that these levels of sibling antagonism invariably spring from ungovernable affection. That is, however, Hákonarson’s ultimate thesis. Before the brothers come to their understanding, various levels of quiet mayhem break out. The calmer Gummi slaughters his own animals. When Kiddi passes out from booze, Gummi picks him up in a digger and dumps him at the hospital.

Featuring wheezing, mournful music by Atli Örvarsson, shot in long creeping takes by Sturla Brandth Grøvlen, Rams sways to the solid rhythms of a harsh land in its harshest season. One can easily imagine such a story being told in the northwest of Ireland, but the picture is soaked in a couched, black humour that speaks of even longer winter nights.

Though the eventual thawing of emotions is properly moving, we remain impressed by the stubborn belligerence of the two men. It’s safe to say that the title refers both to the humans and their charges.