During the Cold War, Soviet agents watch Professor Henry Jones when a young man brings him a coded message from an aged, demented colleague, Henry Oxley. Led by the brilliant Irina Spalko, the Soviets tail Jones and the young man, Mutt, to Peru. With Oxley s code, they find a legendary skull made of a single piece of quartz. If Jones can deliver the skull to its rightful place, all may be well; but if Irina takes it to its origin, she ll gain powers that could endanger the West. Aging professor and young buck join forces with a woman from Jones s past to face the dangers of the jungle, Russia, and the supernatural.