Walden pleads with Kate to give their romance another shot when he's lonely on Valentine's Day. Meanwhile, Alan's holiday with Lyndsey doesn't proceed as he'd hoped.
Berta takes a few days off and Charlie falls for the woman who replaces her.
Charlie spends money wildly for his old lover Courtney, who returns after spending three years in prison.
Alan gets creative with a gift for Lyndsey when he's ashamed that he can't afford an expensive present.
Charlie and Courtney split up, and a depressed Charlie seeks solace from his psychiatrist, Dr. Freeman.
Alan becomes paranoid when Charlie and Lyndsey start to become friends.
Charlie can't get over Rose being married, and he begins to stalk her; and Alan is worried when Jake and Eldridge make videos of each other performing dangerous stunts.
Charlie and Rose's affair continues while Alan's chiropractic business turns shady.
Alan learns Rose's secret when he meets her "husband," and Rose uncovers Alan's Ponzi scheme. Meanwhile, Charlie scrambles to find time to be alone with Rose.
In Part 1 of a two-part ninth-season opener, Ashton Kutcher joins the cast as brokenhearted billionaire Walden Schmidt.
In the conclusion of a two-part ninth-season opener, Judy Greer joins the cast as Bridget, Walden's ex-wife.
Alan gives dating advice to Walden as he prepares to go out with Bridget; and Jake decides to drop out of school because that's what Walden did.
Walden looks for Mrs. Right, and Alan wants Lyndsey back in his life.
Alan has trouble accepting Lyndsey's seedy movie past, and Walden tries to cheer him up by throwing a party.
Walden receives divorce papers, but then he meets a woman who looks just like Bridget.
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