Philip Pullman's thrilling fantasy comes alive in this BBC Radio 4 dramatisation. A breathtaking epic, the award-winning "His Dark Materials" trilogy spans a multitude of worlds. The second instalment, "The Subtle Knife", introduces Will Parry - a young boy in search of his long-lost explorer father. Will's discovery of an extraordinary 'window in the air' near the Oxford ring road leads him out of our world and into the strange and unsettling Cittagazze. There he meets Lyra, a girl who is herself searching for something: the secret of the mystical substance Dust. Moving back and forth through the portal, Will and Lyra join forces in their quest. As they make allies and enemies along the way, they also learn of the subtle knife. An object which many would kill to possess, the knife has incredible powers, and Will finds himself reluctantly in a fight for its possession.