The actress plays a businesswoman with sinister intentions.

On the season finale of "Medium," airing Monday, May 12 at 10 p.m. on NBC, psychic Allison's (PATRICIA ARQUETTE) attempt to ease a young couple's concerns that their "dream home" is haunted leads to unexpected misery and murder, while her husband Joe (JAKE WEBER) must deal with an altogether different threat -- sexy guest star KELLY PRESTON!

"'Medium' really, truthfully, is my favorite show," Kelly tells ET. "My husband [JOHN TRAVOLTA] loves it as well. But my kids -- well at least my youngest, she's a little spooked, I think."

This season's finale, "Drowned World," finds Kelly up to no good in the skin of her character Meghan Doyle, a venture capitalist with some rather shady plans in store for Joe's solar powered invention.

"She keeps sort of pulling him into her web with promise of prosperity and, you know, true realization of his dream," the 45-year-old actress says of Meghan. "Yet, she is sort of taking him down a slippery path."

And while the episode's exciting conclusion marks the end of her story arc, Kelly doesn't rule out the idea that viewers might see her devious double-dealer on the series again -- even if Meghan were to meet her demise.

"My character gets pretty wound up pretty succinctly," she explains. "But, you know, as with a lot of the characters, they can also come back … I don't fall off a cliff, but I do do something that's pretty wicked."