It’s hard to explain the extent to which Expen4bles – a pale imitation of its kick-ass good-time predecessors – is an unrelentingly disappointing movie. Anyone who’s already exited the action-movie all-star franchise, either by their own choice or at the hand of the writers, should consider themselves lucky. Those they leave behind deserve better than Expend4bles’ flimsy nuke-chasing plot and clumsily staged combat. In the nine years that passed…