Movie heroes can be smart or dumb. They can be good or evil, brave or cowardly. But it’s hard to remember an action hero as mind-numbingly dull as John Cena’s Detective Danny Fisher in this ’90s action throwback. Fisher is an everyday New Orleans beat cop, complete with jowly dog, button-cute fiancée and white picket fence, until he accidentally bumps off the girlfriend of sadistic arms dealer, Miles Jackson (Aidan Gillen). In time-honoured bad-guy tradition, Miles isn’t interested in straightforward revenge, preferring to subject poor Danny to the Herculean tasks of the title, which include stopping a runaway streetcar and, er, saving a fat guy stuck in a lift. There’s a decent little action movie somewhere inside ‘12 Rounds’: a bit more complexity of character, a few more jokes and a hero who doesn’t look like a two-by-four with a buzz cut might have gone a long way. As it is, this is occasionally diverting but ultimately laborious.