Elisabeth Moss, Jon Hamm share baggage in ‘Mad Men’

“Playgrounds.”

It’s just one word, but it’s Elisabeth Moss’ favorite line from her four seasons of pretty great lines on “Mad Men.”

Moss delivers that word during the fourth-season episode “The Suitcase,” essentially a two-character show featuring Moss’ earnest copywriter Peggy Olson and her mercurial boss, Don Draper (Jon Hamm). The story takes the characters through the course of a long evening, ending with Don breaking down after learning that his friend Anna, “the only person who really knew” him, has died.

Earlier in the episode, in a bar (where else?), Don asks Peggy if she ever thought about the baby she gave up for adoption. She pauses and then answers, “Playgrounds.”

“The baby had never been mentioned, and here, in one word, the writers communicate the whole story about how Peggy feels about something really big that happened,” Moss says.

It was the last line “Mad Men” creator Matt Weiner, who has sole writing credit on “The Suitcase,” put in the script after a long debate over whether Don should ask the question.

“These are not people who go around talking about themselves all the time,” Weiner says. “It’s a pre-Oprah world. But Don and Peggy have this history and to see them cut through that to actual intimacy was very powerful.”

Moss calls “The Suitcase” a “beautiful gift,” and it’s easy to see why. The episode offers Peggy a parade of brilliant moments — the forced politeness with a very pregnant Trudy (wife to Pete, who also fathered Peggy’s child) in the ladies’ room, the puzzled way she looks at the wall of urinals while Don is vomiting in the men’s room, blowing up at Don and then, later, tenderly consoling him — and Moss nails every scene.

“It was a culmination of four years of developing those two people who had been orbiting each other,” Moss says. “And then it was just me and Jon most of the time in our own little bubble for eight days. I was really sad when the episode was done. It was like the end of a play.”

Says Weiner: “When we were conceiving the episode about a couple of characters, I knew that Peggy and Don — and Elisabeth and Jon — were this incredible duo that were crazy about each other and respected each other. That it worked is a testament to their talents. There’s 48 pages in that script and they’re sharing 44 of them.”

— Glenn Whipp