When she gets there she lives with the Dark Sisters for six weeks until Will comes and rescues her.

Six Weeks Later: Tessa has been held prisoner by the Dark Sisters.

Miranda is a clockwork creature who worked for the Dark Sisters.

Her third novel, "The Dark Sister," takes up the issue in much more complex narrative form.

However, she is approached by two strange women calling themselves the Dark Sisters that give her a letter apparently from her brother.

Six Weeks Later, Tessa is being held prisoner by the Dark Sisters.

If it was a Dark Sister's trick, especially one with a flare for the dramatic, following the instructions could kill her.

"My Dark Sister is here," said Amun, and his voice echoed in Hubbard's head.

Yet why call the Dark Sister by that name?

"It can still happen, even without the Dark Sister."