‘Harry Potter’ stalwart Rupert Grint confirms he has the acting chops for the long haul in this otherwise mediocre Belfast-shot youth flick. It’s familiar stuff: two guys, one girl, guess the rest. As the reserved ginger one, Rupe is hardly odds-on favourite to win the heart of minxy Kimberley Nixon, especially when the competition is rakish, tousle-haired dude Robert Sheehan – his nominal best pal. The ensuing emotional rough-and-tumble proves less arresting than it might have been, however, since the framing device drops too heavy a hint about a fairly obvious outcome, and the inequalities in the performers’ skill levels do tell. Right down to the impeccable Ulster accent, Grint is note perfect, but his playmates struggle to convince, while the directors seem to flap when faced with anything more expansive than angsty interiors. It’s cheering to see a Northern Irish story moving beyond the Troubles, but the merely adequate theatrics on display aren’t noteworthy in themselves. Grint looks set for better things.