From Börkur Jónsson’s ingenious upside-down set to David Farr and Gisli Örn Garðarsson’s subtle direction, this is a fantastic show. Garðarsson is also a wonderfully sympathetic Gregor, the man who wakes up one morning transformed into an unspecified creature – he is referred to as vermin. Kafka’s merry little tale touches on the darker sides of human nature and human interactions, showing how quickly familial bonds break down and how easy it is to change the way people are treated by changing their pronoun: as soon as Gregor moves from a “he” to an “it,” it becomes noticeably easier for the family to ill-treat him.

This is not easy stuff to watch. Kafka’s story, adapted here by the directors, still has the power to shock – and Garðarsson’s gravity-defying scurrying is one of the most disturbing things I have seen in a theatre. It’s a brutal, raw performance. Nick Cave and Warren Ellis’s eerie, atonal score does much to unsettle, too, making this a profoundly uncomfortable 80 minutes. It may be short but it packs a powerful punch and leaves you feeling pretty wrung out.

Kelly Hunter as Gregor’s mother is fascinating to watch; her physicality and movement are superb, and the struggle she portrays between her revulsion at what her son has become and her maternal instincts to protect him is excellently done. Ingvar E. Sigurðsson is less convincing as the father, remaining rather stiff and unsympathetic throughout, but I think this had more to do with English not being his first language – this was a collaboration with Icelandic company Vesturport. The interactions are well-observed, though, and the piece as a whole is utterly gripping. Nína Dögg Filippusdóttir plays Greta, Gregor’s younger sister, with a kind of desperate love which gradually slides into despair, revulsion and hatred. Her portrayal of a sister who tries to overcome her fear to care for her transformed brother starts beautifully, but falters slightly towards the end as she takes control of the situation.

Jónsson’s clever set gives us a normal view of the sitting room, and a dizzying, bird’s-eye view of Gregor’s bedroom above, allowing him to crawl and bound about the set in a most unpleasant way. His other-ness is consistently emphasised by his movement – we are not allowed to forgot that he is a creature – and yet his very human-ness is what makes the play so powerful. As Gregor is dehumanised he is beaten and stripped and dirtied, yet he still speaks English (to our ears, his family hear only a horrible noise) and looks human. Jonathan McGuinness’s unpleasant lodger, who foresees a bright new dawn once “the vermin” are exterminated, makes parallels with Nazi Germany uncomfortably clear, but the subtler references are upsettingly close to the bone, too. There’s a lot of nervous laughter floating about the auditorium.

The piece explores notions of humanity in a fairly heavy-handed way and yet the subtlety of the emotional conflicts presented is so great that the play does not feel burdened by its subtext. I both urge you to experience this profoundly disturbing piece for yourselves, and warn you that doing so will leave you feeling shivery. It’s a compellingly melancholy evening – Kafka would have approved.

Metamorphosis is at the Lyric theatre in Hammersmith until 9 February. For more information and tickets visit www.lyric.co.uk