In the opening episode of the fourth series, trainee doctor Erica discovers that her first patient is Josh, who is about to sign his divorce papers after splitting up with her sister. Erica doesn't think that she can help Josh move forward because she dislikes him, so Doctor Tom tries to help her by getting to the root of her antipathy.

Sam and Erica's mother and father host a lunch for Lenin's parents to celebrate the baby news, but Barb doesn't seem to be taking it well and makes the event uncomfortable for everyone. In an effort to find out what's behind Barb's reaction, Doctor Tom sends Erica back to 1969, when her mother was a 17-year-old high school student.