The Subtle Knife by Philip Pullman

The second installment in His Dark Materials clarifies the Miltonian and Biblical roots of the series. Lyra meets a boy, Will, who also functions as an orphan. At times, the use of both the alethiometer and the subtle knife seem a bit forced, and the power of the forces of the Authority seems a bit exaggerated as they respond so quickly to some things and completely miss other things. Overall, an enjoyable middle book that moves the trilogy along.