Charlie begins a questionable romantic relationship with an ex-patient.

Jennifer moves in with Charlie temporarily and Kate gets jealous.

Lindsay Lohan comes to Charlie for therapy and they begin a tumultuous relationship.

Charlie lets his father help him coach a high school baseball team with bad results.

Charlie shakes up his relationship with Kate while dealing with the return of Jen's ex-boyfriend.

Charlie and Kate try to control their sexual urges as they begin work together on their sex study; Lacey starts a new job as a pharmaceutical rep.

Charlie breaks all the professional rules by starting a friends-with-benefits relationship with a hot woman subject from the sex study. Also, Nolan and Patrick fight over a woman.

Charlie inadvertently picks up the sister of one of his most violent patients at prison.

Charlie is held hostage by his prison group during a riot.

Charlie tries to stop Kate from having sex with the executive in charge of funding their study; Charlie's dad tries to stop Lacey from throwing herself at a sleazy yoga instructor.

Charlie invites a new therapy patient named Bob (Bob Clendenin) into the group, who casually tells everyone that he is the devil. Nolan makes a deal with Bob to sell his soul in exchange for Lacey falling in love with him. When Lacey is all over Nolan at the next session, even the skeptical Charlie starts to wonder. Meanwhile, Jen falls for a new neighbor while Sam falls for a young man who appears to be the neighbor's son, but the two are later revealed to be gay.

Charlie and Sean go to war when Charlie begins having casual sex with his ex, who is Sean's former girlfriend.

Charlie asks for a second chance with the woman to whom he lost his virginity, and Lacey and Patrick try to keep up appearances when Lacey's parents pay a surprise visit.

Charlie is pursued by a hot reporter who wants to experience his sex study.

Charlie convinces Jordan to pose as the fiance'e of a member of his prison group, and Lacey and Patrick gamble away part of Lacey's parents' money.

Charlie falls for the sexy daughter of his father's warring neighbor.

Charlie is inspired to start a new clinic at the prison after Jordan wrecks their sex study.

When Charlie keeps choosing sex over work, Jordan convinces his girlfriend, Sasha, to cut him off for six months.

Charlie goes ballistic when a drunk Jordan makes out with a prisoner.

When Charlie breaks it off with a police officer he's been dating, she abuses her power to make his life miserable. Meanwhile, Jordan struggles to establish a casual sex relationship with Sean.

Sean tells Charlie not to have sex with his visiting sister, and Patrick and Lacey discover that they are dating the same man.

Problems arise after Charlie has a threesome with his girlfriend and one of her friends, and Lacey uses Jordan's help to try and sell her eggs.

Charlie makes a promise to an attractive reporter; it involves an interview with an extremely furious convict.

Charlie gets in hot water with his prison group when he sleeps with the attractive new warden.

Charlie inadvertently helps a member of his prison group in an escape attempt.

Charlie goes to war with his garbage man.

Charlie's life is taken hostage by a controlling techy girl.