Last year's hit The Purge ventured a superficially eyecatching premise – what if the US government granted its citizens an annual mischief night to get any crime out of their systems? – before retreating indoors into indifferently staged runaround. The sequel, again overseen by James DeMonaco, thinks the idea through, following those left outside as the Purge kicks in. Flickers of dread materialise – care of those one-percenters co-opting the event for entertainment – though again we're mostly in second gear. If the first movie was a lacklustre Assault on Precinct 13 (the remake of which DeMonaco penned), this is a modest Escape from New York, with growly lone wolf Frank Grillo steering representative survivors between Gothy bikers and lip-smacking private armies. For Universal, the franchise is a low-risk work-in-progress, but DeMonaco is improving as a shotmaker: this entry just about plays, albeit on the level of a straight-to-DVD item or TV pilot.