The Subtle Knife is the sequel to The Golden Compass, a fierce, solemn, inventive fantasy by Philip Pullman that draws on such unlikely sources as Milton and particle physics. The Golden Compass took place in an alternate world where the Church has retained tight control of science and magic; The Subtle Knife moves back and forth between our world and another.

Will Parry's father disappeared twelve years ago, shortly before Will was born. When menacing strangers come looking for his father's papers, he accidentally kills one of them. Will flees to Oxford, where a stray cat leads him through a hole in the air to Citagazze, the city between worlds, deserted by adults and haunted by invisible Specters. There, Will meets Lyra, who walked out of her world through a breach in the arctic sky at the end of The Golden Compass. While Will and Lyra join forces to search for their fathers, everyone else is searching for them and the treasures they carry: the golden compass and the Subtle Knife of Citagazze.

The story is fast, intricate, and suspenseful, and both Lyra and Will are engaging protagonists. However, The Subtle Knife does suffer from being the middle book of a trilogy; the plot mainly serves to gather all the key figures and move them toward the scene of the next book's climactic battle. The book halts suddenly after a rapid series of disasters, leaving very little resolved and a host of subplots dangling.

The Subtle Knife is a frustrating book, but not nearly as frustrating as not reading it would be. This is one of the most original and absorbing new fantasy series to appear for any age group in the past few years, and I'm waiting anxiously for the final book of the trilogy.