The unholy mix of George Lucas’s colonialist nostalgia and Steven Spielberg’s fluency with action becomes more self-conscious in this fourth Indiana Jones outing. In 1957, two decades after the events of Indiana Jones and the Last Crusade, the hero (Harrison Ford) joins forces with his old flame from Raiders of the Lost Ark (Karen Allen) and a young punk (Shia LaBeouf) to combat a Commie villain (Cate Blanchett, doing a variation on Garbo’s Ninotchka) in a remote corner of Peru. The character and plot contrivances are dumber than ever, but this is basically vaudeville, not narrative, and the thrills keep coming. (Once Indy has survived a nuclear blast early on, going over three waterfalls in a row without wetting his lighter is par for the course.) Spielberg’s extravagant action, much of it staged on what look like old sets from King Kong, includes pointed steals from The Naked Jungle (1954), Land of the Pharaohs (1955), The Ten Commandments (1956), and his own Close Encounters, E.T., and A.I. PG-13, 124 min. (JR)