Welcome back to the future, Claire: In Sunday's episode of Outlander, the time traveler is back in her old Boston hospital to treat a patient and chat with pal Joe Abernathy. The scenes are definitely a departure from The Fiery Cross — the fifth book in Diana Gabaldon's Outlander series on which this season is based. Here, executive producer Matthew B. Roberts explains why it was important to send Claire forward in time, and why he opted on creating a new character named Lt. Knox.

ENTERTAINMENT WEEKLY: I never got a chance to ask you: what inspired the decision to have a choir sing the opening title song?MATTHEW B. ROBERTS: As you know, the main title images and song have continually changed over the seasons to reflect where the characters are in the story.  When we started the post process of season 5, I had heard an emotional medley of “The Battle Hymn of the Republic,” “Anchors Away,” and “The Army Goes Rolling Along” sung by the Annapolis and West Point choirs. And the fact that the Fraser/Mackenzie clans are exponentially growing – I thought maybe we should grow the theme song as well. I asked [music supervisor] Bear McCreary to arrange a few choral variations, and boy did he ever. A few of us were listening to the different versions, and as soon as we finished playing them, everyone simultaneously agreed on “number 2.”

Why the decision to have the flashbacks to the 20th Century, when Claire remembers the death of a patient who had an allergic reaction to penicillin? Also, where did you find that incredible church? 

We like to keep the time travel elements alive in the show. If a viewer was just coming to Outlander in season 5 ... I know, where have they been, right? ... they might not realize that Claire is a time-traveler or that she lived in the future.  So, we combined two stories — one from Voyager and the other from The Fiery Cross — that mirrored what she was going through in [her] present. Our fantastic locations department found the church in Paisley just west of Glasgow.

Knox is a new character. Did you have to create him because of the ongoing story with Murtagh? 

There was a character in the book, Lt. Hayes, that comes to the Ridge to put pressure on Jamie regarding the Regulator uprisings. So, in keeping with that, we had Tryon put the pressure on Jamie by leaving Lt. Knox and his platoon to hunt down Murtagh. But instead of having Knox be an adversary, we flipped it. Knox and Jamie actually begin to bond. Knox becomes enamored of the life Jamie has carved out of the wilderness, and under different circumstances, perhaps Jamie and Knox could have been close friends.

Outlander airs Sundays on Starz.

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