She's actually in a couple scenes. I'm pretty sure that's her in the temple. There is another shot with her and the captain looking out over a vista together. She is also seen brandishing a bow and arrow, if I am not mistaken.
I postulate that Book is actually "re-imagined" as the Assassin.
Re: Inara is there.
I postulate that Book is actually "re-imagined" as the Assassin.