In the far-flung future of 2230, Dr. Mark Savant (yes, that's his real name) has heard that the world of Genero has taken up human sacrifice!!
Savant goes there, and quizzes King Gaarlo about what the hell is going on!
And in a totally unsurprising twist, the trainee turns on the trainer:
From Amazing Ghost Stories #16 (1955). Yes, I know there are no ghosts in this story...