Mola Ram's brother, Bolo Ram, joined the Nazis to relocate the stones. Indy goes after him in 1945 when the Nazis are trying to smuggling their ill-gotten gains out of Germany aboard a train. 22 years later, old Indy is hired to track down the ex-Nazi Bolo Ram in the jungles of Argentina where he's hiding out with Dr Mengele using the stones to bring back the Third Reich. A nonsense reporter and feminist upstart tags along for the ride.
Its true. All of it.