Rockmond Dunbar,  Simon Baker Rockmond Dunbar, Simon Baker

As The Mentalist moves to its new timeslot (Wednesdays, 8/7c) tonight, Dennis Abbott (Rockmond Dunbar) gets a not-entirely-welcome blast from his past that could derail his career - and possibly his wife's as well, as she's being vetted for a position in the Department of Commerce.

"There's some things in [Abbott's] past that are a little sketchy," Dunbar tells TVGuide.com. "There are some choices that [he] made back in the day ... that'll jeopardize her being confirmed."

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The skeleton in Abbott's closet stems from a botched operation in Mexico when he worked with ATF years prior. Dylan Baker guest-stars in the episode as Abbott's former boss Peterson, who tries to blackmail him into keeping mum about a botched DEA raid in present day.

As he tussles with Baker's character, Abbott finds an unlikely ally in Jane (Simon Baker), who sees a different side of his new boss and, in the exclusive sneak peek below, gives Peterson a taste of his own manipulative medicine in order to protect Abbott.

"[Jane and Abbott] had a chess match at the beginning, me figuring him out, him figuring me out - him figuring me out way quicker than I'm figuring him out, because he is the Mentalist," Dunbar says. "But it's really nice to have these two guys have a mutual respect and a friendship that blossoms."

But don't expect Peterson to back down right away. Wednesday's installment is the beginning of a multi-episode arc that pits Abbott against his former superior. "Dylan and I go at it," Dunbar says. "It's going to be a little bit messy and you're going to see two men handle a desperate situation in a desperate way."

Check out am exclusive sneak peek from "Green Light" below.

The Mentalist airs Wednesdays at 8/7c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)