Star Trek episode "The Omega Glory"
"The Omega Glory" Season 2, Episode 23. Okay, this one wins the Planet-of-the-Apes award for strangest ending. You'll see what I mean. The Enterprise comes to the planet Omega II and finds the USS Exeter already in orbit. The Exeter is empty. Only uniforms are left and the people have been turned into crystal powder. McCoy says the water was removed from their bodies. Contamination again! Some disease! Amazing how they have no procedures for this. So they beam to the planet and McCoy discovers a "natural immunization from the planet itself." Captain Ron Tracy of the Exeter is alive and well on the surface, apparently in charge and messing with the people, violating the Prime Directive. Tracy says, "None of us will ever leave thi planet." Tracy shoots and kills red-shirted Lt. Galloway and takes over. McCoy finds that there is no disease on this planet and indigenous people like Wu are 462 years old and his father is over 1,000. McCoy disc