Bruno Mars is gearing up to drop his sophomore effort on December 11 and he's just unveiled the lead single. 'Locked Out Of Heaven' carries a slight reggae vibe and is a fairly chilled, sensuous pop offering. Catchy too. Production comes from big names Mark Ronson, Jeff Bhasker, Emile Haynie and The Smeezingtons. Thankfully, it's not a case of too many cooks gathered around the desk. Check out the Hawaiian star's return below.