"The Mentalist" season 6 episode 18 spoilers are up and Patrick Jane goes undercover once again as he tries to take down the filthy rich. Called "Forest Green," veteran actor James Patrick Stuart will guest star in the episode with the tagline "which one percenter is 100% guilty?"

According to the official "The Mentalist" season 6 episode 18 spoilers by CBS: "When a woman is found murdered near a remote men's social club, Jane must find a way to insinuate himself into the insular group to find the killer."

Will the filthy rich be any match to Patrick Jane (Simon Baker)? He will be rubbing elbows with the powerful and influential as he infiltrates a very exclusive men's club. This episode will be directed by Eric Laneuville and written by Jeffrey Hatcher.

Aside from James Patrick Stuart who plays Gregory Dyer, other guests include Jon Abrahams (Peter Kilgallen), Camryn Grimes (Deanne Price), Natalie Padilla (Madison Pince), Mark Harelik (Kenyon Russell), Elizabeth Chomko (Pam Parons), Sonny Marinelli (Marvin Gryska) and Ellen Wroe (Officer Green.)

For more "The Mentalist" season 6 episode 18 spoilers, this corner will certainly report them as soon as they come.

The last time Patrick Jane went undercover was for "The Mentalist" season 6 episode 16 called "Violets" where he and Teresa Lisbon (Robin Tunney) passed themselves off as a couple in an entrapment operation to bring down the art thieves.

The episode was also made more significant because it was the first time that viewers were introduced to Agent Marcus Pike (Pedro Pascal) who will soon throw a wrench into the whole Patrick Jane-Teresa Lisbon romance.

According to executive producer Bruno Heller as reported in Entertainment Weekly, it's crucial for Teresa Lisbon to step away from partner Patrick Jane and "see herself for herself" and that's why Agent Marcus Pike was created.

"In order for her to fulfill herself -- even if she eventually fulfills herself with Jane, which she may or may not do -- she has to find other relationships, other perspectives, other people who love her, just to feel fully who she is," he said.