Masters and Johnson take comments from the press regarding the publication of their upcoming book Human Sexual Response. In flashbacks to the previous summer, the Masters and Johnson families vacation together at a lake house. Libby attempts to remedy her depression.
Johnson takes a leave of absence as she undergoes a pregnancy. To give her partnership with Masters legitimacy, she agrees to remarry George. The Shah of Iran and his wife seek fertility treatment from Masters.
Human Sexual Response is published and receives a mixed response from the public. Masters wants the book to be utilized as a textbook while Johnson seeks an investor for the clinic. Libby gives support to her neighbor. Tessa's experience at school is impacted by her mother's work.
Johnson receives a worrying letter from her son in Vietnam and finds support in the clinic's new investor, Dan Logan. Masters attempts to soften his personality. Libby helps her neighbors recover from a tragedy. Margaret tries to adapt to a much different kind of relationship.
Masters is invited back to Washington University to deliver a speech after the success of the book. Johnson's parents arrive unannounced. Religious fanatics protest the clinic. Johnny is bullied at school and Masters seeks justice.
The Masters and Johnson clinic take on a high-profile Hollywood couple. Johnson reaches her breaking point with her mother. Masters attempts to reinvigorate his relationship with Johnson just as Logan attempts to pursue her. Libby discovers Joy's secret apartment.
Masters and Johnson are enlisted to apply their sexual dysfunction remedies to a gorilla. Johnson's relationship with Logan deepens. Masters is enticed by the idea of surrogate work. Betty and Helen want a baby and weigh their options. Libby begins an affair with Paul.
Johnson and Logan disappear to Las Vegas for a weekend. Masters uses her absence to launch the surrogacy program despite Johnson's reservations. Betty, Helen, and Austin participate in an elaborate ruse to get pregnant via the clinic. Libby gives Paul insight into her past affair.
Johnson returns from Nevada incensed by Masters launching the surrogacy program behind her back. Her objections to the program ultimately fall on deaf ears as Masters develops a bond with one of the surrogates. Logan's research at the clinic hits a dead end. Austin seeks comfort from Betty and Helen after he loses custody of his children.
Masters becomes desperate in his efforts to repair his relationship with Johnson. In his fervor, he agrees to sacrifice the surrogacy program. Libby's birthday approaches and the men in her life aim to please. Johnson's relationship with her daughter deteriorates. Barton goes out with a co-worker.
In the aftermath of a tense meeting with their publisher in New York, Masters organizes a dinner with Johnson, Logan, and Mrs. Logan. As the night unfolds, Masters' true intentions are exposed. Libby discovers that Masters is being investigated by the police.
Masters and Johnson are faced with trumped up prostitution charges, an ill-timed event to promote their next book, and the possible disintegration of their partnership. Logan returns from Mexico an unmarried man. Libby announces she's leaving Masters. In a last-ditch attempt to win over Johnson, Masters professes his love for her.