(I'm setting this up early because I'm in a meeting all day and have no idea when I'll be home. Plus, I'll likely watch the Emmys tonight - If I'm lucky - and catch up on Mad Men tomorrow evening.)
Season 3, Episode 6: "Guy Walks Into an Advertising Agency"
A surprise visitor shows up at Sterling Cooper; Sally gets spooked by something (or someone); and Joan is the recipient of some surprising news.
As always, remember to track the conversation.