In 1961, the 23-year-old heir to one of the world's greatest fortunes vanished without a trace off the coast of Dutch New Guinea, and history split in two. One version is a tragic drowning at sea. The other is a chilling story of colonial blowback, a sacred headhunting ritual, and a decades-long geopolitical cover-up.

This episode sifts through Carl Hoffman's investigation, the memoirs of Michael's twin sister Mary, and declassified Dutch colonial files to weigh both theories. We trace Michael's pivot from Harvard to anthropology, his fatal decision to swim for shore after two days clinging to a capsized boat, and the cultural and political forces, including a 1958 massacre by Dutch authorities, that may have sealed his fate.

• Michael abandoned his overturned 40-foot dugout canoe and swam for shore using two cans and a gas tank as ...