This likely is the first chapter of Series F.
At the end of the last chapter, Heyoke briefly talks to Serinth about her loops through the Deadwood, asking if she's really finished what she set out to do. Which she confirms. Heyoke is cautiously excited.
Heyoke: So it's finally over?
Heyoke (cont'd, expression somewhat sadder): And none of us survived?
Serinth: Not none of us.
That dialogue is a little awkward, but the point is we then jump to Series F, a new series. And we show that Pyren is still alive and roaming through the Deadwood from Serinth's previous loop. He's thinks he's finally going to regroup with her, but instead he just finds her corpse and the corpses of Heyoke and Jagex. We segue into the his final scenes in Book 3 where he's confronted by the tiger monster, given the stuffed tiger as a gift, and led to Bambi giving birth to the lion cub.