Woody Allen’s career has been on a downward trajectory for some time now, but Cassandra’s Dream marks the point at which it drops into a woozy nosedive. Like his two previous films, Match Point and Scoop, it is set in Britain, where the light, Allen says, is ideal for his style. The light isn’t the problem with Cassandra’s Dream, however. It’s the plot. And the script. And the acting.

Ewan McGregor and Colin Farrell play London brothers whose dreams of buying a yacht teeter on fulfilment when their highflying Californian uncle (Tom Wilkinson) offers them a sackload of money to murder a troublesome business rival. The ingredients, one might think, for a wry comedy. The trouble is that Cassandra’s Dream is a drama. It is just about conceivable that Allen might assume that all Britons live either in poky terraces or expansive stately homes, but McGregor’s Cockney accent is unforgivable.

The central premise is also acutely feeble – why would two financially challenged but far from destitute men agree to such a radical proposal? – while the clumsy allusions to Greek tragedy as the pair agonise over their crime smack of a sixth-former’s attempt to inject profundity into a D-minus essay. The whole thing plays like a below-par episode of EastEnders crossed with a below-par episode of Howard’s Way. How the mighty have fallen.

12A, 108mins

Editor's choice

• U2 at Nou Camp Stadium, Barcelona
• The 50 Best Movie Villains
• The 15 golden rules of theatre etiquette