Mad Men Season 5 Episode 3 (04/08/12)
Don and Megan run into one of Don's former lovers. Megan gets jealous, and brings the conversation into play. She wonders if it was Betty that drove him to cheat all those times, or if it is just a part of him.
Don is sick all episode long, goes home to rest, but the former partner follows him home. She tries to sleep with him but Don sends her home. She comes back, they have sex, and he strangles her to death, but we then realize it was a hallucination due to the fever.
Greg comes back from the war and reunites with Joan. He tells her they're calling him back for a year, and she's upset. She gets more upset when she finds out he's volunteering. Joan finally had enough, and kicks Greg to the curb.
After working all night for Roger, Peggy finds Dawn sleeping in Don's office. She brings the secretary home and they bond over being the only one of their kind at the office.