In this image released by AMC, Don Draper, portrayed by Jon Hamm, appears in a scene from the second season of "Mad Men." One of the most common theories about the end of "Mad Men" is that Don Draper dies. THE CANADIAN PRESS/AP/AMC, Carin Baer

TORONTO - One of the most common theories about the end of "Mad Men" is that Don Draper dies.

The most recent episode does nothing to dissuade that idea. Some online prognosticators have pointed to potential clues that the charismatic chameleon has shed his slick ad man persona and is set to reclaim his real identity as Dick Whitman.

Of course, staff writer Semi Chellas won't address any of the finale speculation — although she could spill plenty. The Calgary-bred scribe co-wrote this past Sunday's episode with series creator and former "Sopranos" writer Matthew Weiner.

Reached this week by phone in Los Angeles, she'll only admit this was "a big watershed episode for a lot of the characters in different ways."

Don was last seen picking up a shaggy-haired hitchhiker on his way to St. Paul, Minn., and Joan accepted a much-devalued buyout when it became clear she would never be able to maintain the hard-earned status and respect she developed at SC&P.

And was that some kind of "Sopranos" in-joke when Joan's boyfriend Richard suggested she "call a guy" to take care of her workday woes?

Chellas says she's busy working on another prestige drama these days — season 4 of the Toronto-shot Space series "Orphan Black," created by high school sweetheart John Fawcett and old pal Graeme Manson.

But she took time out this week to address Don's impromptu road trip, Peggy's vermouth bender, and Joan's last stand at McCann:

CP: What's going on with Don?

Chellas: Jim Hobart said to him that he bought an agency so that they could have Miller Beer for Don to work on, and I don't think Jim Hobart was trying to trick him at all. I think that's just the way it works at McCann, but when Don walked into that meeting and saw all those creative directors and realized what it was ... he got up and he walked out.

CP: And does he have a plan?

Chellas: I think he doesn't know where he's headed at that point. Or wouldn't be able to tell you where he's headed or why.

CP: Have you read these predictions online that Draper's days are numbered?

Chellas: The show and Don Draper have always had an obsession with death but also the beyond, with a sort of question of: What's it mean? And what's it for? And what's out there?

I think that those questions are intensifying within the character — and for obviously the audience — as we get towards the end.

CP: Joan's boyfriend Richard (played by Canadian Bruce Greenwood) seems too good to be true.

Chellas: I love that character. They didn't start in the greatest place because when she told him about her son in that episode he pulled a runner. And he came back to her and I think she means something to him but they have a problem built in — he is a retiree and was looking to pursue his dreams. Again, I'm not going to speak to how their relationship will come to pass but it's definitely not too good to be true.

CP: At least we'll get to see Joan again. Every time I watch I wonder if that's the last time I'll see certain characters.

Chellas: Well, at some point it will be. There was a sense all through the last seven (episodes), all through this season in the (writers') room, of: Is this the last scene between these two characters? Is this the last time we'll see this character?

Sometimes you have a plan for something more and then you literally don't have room or time. I think we focus on telling really great stories right up until the end, rather than a whole season built on a series of valedictions.

CP: Peggy and Roger had an amazing scene together.

Chellas: I love them together and it was nice to think of them in that empty building. I think Roger's reflecting ... he got something from his father with their name on it, he built it into something else ... and now it's being absorbed into McCann and there goes his name and there goes his legacy, as he talks about with Don in the last episode.

And yet Peggy's the one saying, "I hope I have that problem someday." She would love to have her name on the door someday, so in some sense, this is a move for her. It's the beginning of something. CP: How did you end up writing this episode?

Chellas: The last couple of seasons I was running the (writers') room so I knew that I would have a late one, because I had to sort of be there until the end, and I felt really lucky to land that episode.... But it's a hard episode. Don leaves his whole context and goes off and Peggy's alone for much of it. It was a challenge. I think of all the scripts that I've written for "Mad Men" (this) did feel like a completely new challenge of how to do something I had never done before.

— This interview has been edited and condensed

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News from © The Canadian Press, 2015