Vesper: The Archimerist (Vesper #2)

Accompanied by Zarak, a mischievous familiar who doubles as a deadly weapon in battle, Vesper sets a course for Valestiel, where Prince Crimson Nyx is thought to be imprisoned. She knows she cannot free him by herself, however, so she decides to call upon the help of her former companions, the Knights of Nyx. But she will have some convincing to do, given the steep losses the Knights have already incurred. Beyond that, a crucial question remains: is Crimson even still alive? And if so, in what state? More than their own lives will be at stake when Vesper discovers the truth, as she is moved in her desperation to an act of folly...