Franz Kafka's famous short story is based on a simple but audacious premise: a young commercial traveller, Gregor Samsa, wakes one morning in the family home to find he has been transformed into a giant insect.

The rest of the story explores the impact on his parents and sister, who are economically dependent on the young man. Ironically, their rejection of him, and the necessity for them all to take on menial employment, ultimately leads them to a feeling of empowerment.

Inevitably there has been much debate about the meaning of Kafka's allegory, which appears to reflect his own troubled relationship with his father. In this production from Icelandic company Vesturport and the Lyric Hammersmith, adaptor David Farr has added a couple of signposts in the proto-fascist parting shot of Gregor's employer and the militarist enthusiasm of the lodger taken in by the family after Gregor has been confined to his room.

The story was written in 1912 and published during the First World War. How many gravely injured young men would become Gregor-like burdens on their families in the next few years?

On the face of it Metamorphosis is extraordinarily unpromising material for the theatre. But Steven Berkoff made his version as long ago as 1969, and with the rise of the physical theatre movement it presents a tempting challenge.

But for me that's just the problem. Bjorn Thors's acrobatic performance is a virtuoso affair, but in the context of Kafka, theatrical virtuosity seems beside the point.

Watching this visualisation of the story, with a naturalistic two-storey set in which Gregor's bedroom has been crazily turned upside-down, is not uninteresting. But ultimately it's no match for reading Kafka's original story - and it takes longer.