There are shades of Sightseers (Ben Wheatley's Bonnie and Clyde-style serial murder comedy which was, surely, the worst film of 2012) in Solstice, an attempted thriller by Angela Ness and Glen Davies.

In a croft in the north of Scotland, we find a couple (a combustible Englishman and a seemingly distraught Scottish woman many years his junior) standing over the wrapped body of a man they have just murdered. The reasoning behind the killing changes as Ness and Davies turn the play on its head.

With the drama's central twist comes a shift into the territory of David Harrower's great play Blackbird. However, the subject matter is just about all Solstice has in common with Harrower's piece.

The unexpectedness in Ness and Davies's drama is punctured by moments of dreadful predictability. Add to that some terribly clunky writing, a series of witless attempts at comedy and palpably uncertain acting from Annabel Logan and Mark Kydd.

Although it never quite plumbs the depths achieved by Wheatley's film, Solstice is an uninspired, unsubtle and flat hour of theatre.

Assembly Roxy, 0131 623 3030, until 26 Aug (not 12 and 19), 1.45pm, £10.