Scooby-Doo, Where Are You! (1969)

S01E06 What the Hex Going On?

The group witnesses a mysterious individual entering an eerie estate. They discover he is acquainted with Uncle Stewart. Stewart reveals that the spirit haunting Kingston Mansion is responsible for his accelerated aging. As odd occurrences unfold, Sharron and Uncle Stewart suddenly go missing, leaving the gang to unravel the mystery.