A taboo office romance is revealed. At a brainstorming session, Peggy proves to be more than a secretary, opening up new opportunities for her at Sterling Cooper. Meanwhile, Rachel faces her conflicted feelings for Don after he seeks out her advice on a new campaign.

Don is tormented as pieces of his secretive past begin to haunt him. Peggy's new success at work, and resulting boost in confidence, threaten her office relationship. Salvatore Romano gets a little too close with a client.