Betty discovers that she has a tumor, Peggy interviews an obnoxious young copywriter for a job, the firm tries to get the Mohawk Airlines account back, and Don and Harry try to court The Rolling Stones to record a commercial.
Don gets a visit from the in-laws and his children just as he's about to receive a prestigious award and tries to save the Heinz account. Meanwhile, Peggy and her boyfriend take the next step in their relationship.
A depressed Betty tries to make things uncomfortable for Don and Megan, Roger tries to take out some secret weapons for a meeting with a prospective Jewish client, and Don makes a snap judgment that angers the creative department.
Lane searches for a way to get rid of a sizable debt, the firm prepares to pull out all the stops when it gets a second chance to land Jaguar as a client, and Don tries to comfort Joan when she reaches her breaking point.
Peter asks Joan to make an unspeakable sacrifice to help secure the Jaguar account, Peggy prepares to make a drastic move in response to Don's treatment, and Megan's acting career begins to create tension with her and Don.
As the partners consider expanding the office space, Don begins seeing ghosts and gets a request to advance Megan's acting career. Meanwhile, Peter's affair comes to a disappointing end, and Megan's mom briefly reunites with Roger.