<P> The film premiered at the 2008 Cannes Film Festival on May 18, 2008, and was released worldwide on May 22, 2008 to generally positive reviews from critics, although audience reception was more mixed . There was significant praise for the performances, action scenes, John Williams' musical score, and the costume design . Criticism, however, focused on the dialogue, storyline, pacing, and overuse of CGI . It was also a financial success like the previous three films in the series, grossing over $786 million worldwide, becoming the franchise's highest - grossing film when not adjusted for inflation, and the second - highest - grossing film of 2008 . The film will be followed by an as yet untitled fifth film planned for release on July 10, 2020, for which both Spielberg and Ford will return . </P> <P> In 1957, Indiana Jones and his partner George "Mac" McHale are kidnapped by Soviet agents under Colonel Dr. Irina Spalko, who infiltrate a warehouse labeled "Warehouse 51" and force Jones to locate a mummified corpse recovered from a crash site . Upon its discovery, Mac reveals he is a double agent working for the Soviets . Jones escapes and unsuccessfully attempts to retrieve the body . After a fight with Spalko's sadistic henchman, Colonel Antonin Dovchenko, Jones escapes to a model town at the Nevada Test Site minutes before an atomic bomb test, and takes shelter in a lead - lined refrigerator . Jones is rescued, decontaminated, and apprehended by FBI agents, who suspect him of working for the Soviets; though freed on the recommendation of General Ross, who vouches for him, he is put on indefinite leave of absence from Marshall College . His leaving also causes the dean's resignation to keep Indiana's job at the college . </P> <P> Jones is approached by greaser Mutt Williams, who tells him that Harold Oxley had found a crystal skull in Peru, suffered a mental breakdown and was later kidnapped . Jones tells Mutt about the legend of crystal skulls found in Akator . Mutt gives Jones a letter from his mother, who is also held captive, containing a riddle written by Oxley in an ancient South American language . KGB agents attempt to capture them, but Jones and Mutt escape them and reach Peru . At the local psychiatric hospital, Oxley's scribbles on the walls and floor of his cell lead them to the grave of Francisco de Orellana, a Conquistador who searched for Akator . They discover the skull at the grave, with Jones reasoning that Oxley had returned it there . </P> <P> Jones and Mutt are captured by Mac and the Soviets and taken to their camp in the Amazon jungle, where they find Oxley and Mutt's mother, Marion Ravenwood, who reveals that Mutt is Jones's son, Henry Jones III . Spalko believes the crystal skull belongs to an alien life form and holds great psychic power, and that finding more skulls in Akator will grant the Soviets the advantage of psychic warfare . Spalko uses the skull on Jones to enable him to understand Oxley and identify a route to Akator . Jones and his four allies escape with the skull, but Marion and Jones get caught into a dry sandpit, to be recaptured by the Soviets after Oxley accidentally brings them as assistance . On their way to Akator, Mac tells Jones he is a CIA double - agent to regain Jones's trust, and Jones's team fights its way out of the Soviets' clutches, while Dovchenko is devoured by siafu ants . Jones and his allies cause many of the Soviets to fall from a cliff, and they survive three waterfalls in an amphibious vehicle . Jones and Oxley identify a skull - like rock formation that leads them to Akator, unaware that Mac lied about being a CIA agent, is still loyal to Spalko and has been dropping transceivers to allow the surviving Soviets to track them . </P>

Indiana jones and the kingdom of the crystal skull explained