Kalaziel is a terrible guardian angel: her temper's shorter than she is, she swears, she's missing a wing, and she sees no problem with letting man make their own choices-no matter how questionable. That's what free will is all about, right? Her overseers disagree. After she mishandles an assignment, Heaven strips Kala of her title and throws her back into training, hoping to reinforce the covenant of vows she swore to uphold as a guardian. But the...