What's the most astonishing dark act of screen comedy you can think of? Think dirtier than The Dirties. Holidaying with Sightseers. Faultier than Fawlty Towers. Terrorising with Four Lions.

Under the Tree raises – or possibly lowers – the bar for the nastiest, meanest, pettiest act committed by seemingly ordinary folk.

We’re told that good fences make for good neighbours but even Donald Trump’s wall couldn’t made a dent in the simmering feud at the black heart of this killer – literally and figuratively – Icelandic comedy.

There are layers to the arbitrary and arborist conflict. A tree on the front lawn of Inga and Baldvin’s house is casting a rather large shadow on that of their neighbours, Konrad and Eybjorg. Despite repeated, polite requests from the latter couple, the elderly Baldvin has failed to trim the offending tree, and his properly evil wife, Inga (the magnificently witchy Edda Bjorgvinsdottir), is in no mood to pitch in.

Obscene

Inga’s bitter, post-menopausal rants against her neighbour’s younger, fitter wife become increasingly obscene upon learning that the couple are trying for a baby. “At her age?” she hisses. “At least she takes care of herself,” mutters her downtrodden husband. The warring chatter just keeps on coming.

This unhappy family unit are made even more miserable when their adult son, caught by his wife watching DIY porn made with an ex-girlfriend, moves back in with his parents.

And then the cat goes missing. All bets are off.

Anglophone viewers may well have happened on director Sigurðsson second-hand through David Gordon Green's wonderful Prince Avalanche, a 2013 remake of the Icelandic auteur's Either Way. A remarkable writer-director gifted with razor-sharp wit and an uncanny grasp of human foibles, Sigurðsson is the best approximation to a 21st century Billy Wilder that contemporary cinema has to offer, and Under the Tree falls somewhere between the Some Like It Hot director and the work of the marvellous Austrian miserabilist Ulrich Seidl.

Timber!