Spoiler
Murtaugh....you mean him and Claire discussing her real past? I THINK it's present in the books (don't quote me on that) but it may not be and if not then I'll wager the show is just doubling down on it. Plus she tells Murtaugh everything she tells Jaime.
As far as Brianna...for non-book readers Brianna is a HUGE bomb drop. I think even more than the revelation that Claire goes back to the 1940's and reunites with Frank. She HAS been cast (Sophie Skelton), and I'll wager that Starz is just holding that reveal in check so they can open the season with it.
Also, she's GORGEOUS.
As far as Brianna...for non-book readers Brianna is a HUGE bomb drop. I think even more than the revelation that Claire goes back to the 1940's and reunites with Frank. She HAS been cast (Sophie Skelton), and I'll wager that Starz is just holding that reveal in check so they can open the season with it.
Also, she's GORGEOUS.