This is very much a vehicle for Vin Diesel to flex his muscles and engage in 2 hours of kick-ass adventure. The plot is pretty unimportant: "Riddick" arrives on a planet and is soon hired by Dame Judi Dench to go up against the brutal "Necromongers" - a sort of intergalactic cricket led by Colm Feore, who are hell bent on destroying humanity. After quite a long, slow, start it does not hang about; we have loads of decent special effects as he is double-crossed, imprisoned and ultimately joined with Karl Urban and Thandie Newton to take on the army of locust-like beasties. It's not the best of ...