What the Hex Going On?

What the Hex Going On? is the sixth episode of the first season of Scooby-Doo, Where Are You!

Premise
Mystery Inc. is headed to their friend Sharon Wetherby's estate. When they arrive, Sharon's Uncle Stuart disappears, and when they find him, he says he was beckoned by the voice of the Ghost of Elias Kingston from the Kingston Mansion. The gang find themselves wrapped up in the tangle of the spooky ghoul of Elias Kingston who wants the family treasure.

Synopsis
A ghostly voice calls out from a spooky mansion, beckoning to a man walking in a trance. On their way to visit their friend Sharon Wetherby, the Mystery Inc. gang see this odd sight. When they arrive at the Wetherby's, they learn that Sharon's Uncle Stuart is missing, and they deduce that he was the man they saw going into the deserted Kingston mansion. Investigating, the gang find Uncle Stuart, but he has been transformed into an old man. He tells them that he was called out of the Wetherby house by the ghost of Elias Kingston, who demanded that the Wetherby fortune be surrendered to him, otherwise he would put an old-age hex on the family; he turned Uncle Stuart into an old man as a warning.

While Mr. Wetherby goes to speak to the sheriff, the gang stay behind with Sharon and her enfeebled uncle. The voice calls again, and Stuart walks out in another trance. When Scooby wakes the gang, they find that not only is Stuart gone, but Sharon is missing also. They go to the Kingston mansion to investigate. Their first clue is a watchdog that has been left to guard the mansion: what does a ghost need with a watchdog? Then they find the mummified bones of Uncle Stuart, who apparently had another run in with the ghost. Finally, Elias Kingston himself appears and repeats his threat to the kids. They watch as he disappears into the Kingston family mausoleum in the cemetery next door and follow, noting that this supposed ghost has left behind fingerprints on the doorknob to the crypt. Inside they find a book on crystalomacy, but are trapped when the ghost locks them inside. They find a secret entrance out of the crypt and follow up on the crystalomancy book by going into town to consult a swami. The swami is out, and Scooby winds up impersonating the swami when a customer unexpectedly enters. After the customer leaves, the face of Kingston appears in the crystal ball and the table levitates, chasing them about the room. It crashes, revealing a fan-like motor beneath, and more clues quickly reveal themselves: packed suitcases, a professional make-up kit, and a closed circuit TV camera, suitable for broadcasting images onto the crystal ball.

Back at the Kingston mansion, the gang lays a trap for the ghost. Shaggy and Scooby lure him out with a chest that is supposedly holding the fortune, which, instead of the Wetherby fortune, contains a water-squirting jack-in-the-box. They then use footage of the ghost himself with the special camera to frighten him into a trap.

Back at the Wetherby estate, the ghost is unmasked as Uncle Stuart. It turns out that he was greedy and wanted the family fortune all to himself, so he decided to disguise himself as the ghost of Elias Kingston in order to trick the family into giving it to him, and used make-up to make himself look older. When Stuart is asked why he conspired against them, Sharon and Mr. Wetherby decide to let him explain his purpose to the sheriff as the group celebrates with dinner.