Here is where Serinth tells Jagex "It would only scare you." (when he demands again to know where they're going after she originally says Tairon.)
Yo, actually as she's walking after Pyren she's stopped and someone (maybe Sulin or Sabriel) asks "Serinth. What happened to you in that library?" and she looks back and merely says "It would scare you."
During the camp fire scene she reiterates that it's all 'according to plan.' while staring off at the distance, bored, as if that's enough of an explanation to her pack's queries.
Serinth isn't even looking at the group while they speak until Jagex yells "Answer me! (bitch)" and she turns to him and he says "You said we were going to Tairon." and she says "We are going to Tairon." and he says "Through the fucking Deadwood?!" and she just replies "Yes."
Perhaps this is where Sulin insults Jagex as "Little Prince" or something and Jagex replies he's not a prince, his father was never a king, he was elected democratically, something Weston has forgotten about. (If so, this would go right after Sulin explains he has "nothing but respect for the Wolves of Weston.")