When he’s forced to relocate his study to a St. Louis brothel, Masters has no choice but to rehire Johnson in order to make things work.

As Johnson bristles at the hiring of a new female doctor, Masters worries that conducting their study in a brothel is jeopardizing the results. Haas fights to be allowed to deliver quadruplets.

Painful memories of his childhood cause Masters to question his own ability to be a good father. Johnson is surprised by the arrival of her ex-husband.

As Masters is haunted by memories of his childhood traumas, Haas looks to advance his career by dating Scully’s teenage daughter.

As Masters and Libby struggle with the fallout from her miscarriage, Johnson proposes a study that challenges Freud’s theories of female sexual response. An unsatisfying sex life at home leads Margaret Scully to volunteer for the study

When he and Johnson study their own sexual relationship, Masters must deal with the consequences in his marriage. As Margaret uses her husband’s business trip to spend time with Langham, a mugging puts Scully’s secret life at risk of being exposed.

As Masters and Johnson set out to film their work, the end of her affair leads Margaret closer to the truth about Scully’s secret.

As Masters and Johnson push the filming of their subjects to a risqué and possibly illegal level, their intimate rapport causes his mother to question the relationship.

As the hospital is preoccupied with a nuclear disaster drill, a study participant’s pregnancy further divides Masters and Johnson. Margaret learns the truth about her husband, and Haas finds his days at the hospital may be numbered.

As Masters struggles to carry on without her, Johnson looks to help Dr. DePaul promote her work on women’s health. When Haas babysits while Johnson attends a conference, he squares off with her ex-husband.

Masters’ presentation of the sex study to his colleagues ignites a firestorm of protest and leaves Johnson struggling with the fallout. Scully tells Margaret the truth about his sexual history, while Haas looks for a job in California.