Handsome, muscular, and the son of a superstar, he was naturally pushed into acting, and in 1962 appeared in the swashbuckling Son of Captain Blood, a sequel to his father's Captain Blood (1935).
Besides, Sean didn't care for acting. He wanted to be a real-life adventurer, like Richard Halliburton and Michael Rockefeller. He moved to Africa to become a hunter and game warden. Then he became a photojournalist, covering the Vietnam War and the 1967 Egypt-Israeli War for Paris-Match.
His mother spent years searching for him, and eventually found evidence that the two were captured by the Khmer Rouge or Viet Cong, imprisoned for a few months, and then executed.
A tragic end to a fascinating life.
Of course, you're wondering: was he gay or bisexual?
Sean's friend Perry Deane Young (left, the one with the bulge) doesn't say anything about Sean's same-sex interests in his memoir of their Vietnam experiences (published in 1975). But then, one wouldn't expect him to.
However, it is compelling to note that Sean spent his life surrounded by attractive men.
See also: The Disappearance of Michael Rockefeller; The Disappearance of Richard Halliburton.