Wait, what? (Patreon)

Deep into the book we get Lady A's mental state as she ponders her revenge on Caswell. For what, I've either forgotten or it's, surprise, unclear : 

"She [Lady Arabella] must lure him to the White Worm’s hole–but how?"

I THOUGHT SHE WAS THE WHITE WORM?! DIDN'T WE ALREADY WORK THIS OUT, FOR THE LOVE OF ALL THAT IS GOOD AND HOLY?!?!