Malcolm Polstead's life in the pub beside the Thames is safe and happy enough, if uneventful. But during a winter of unceasing rain the forces of science, religion and politics begin to clash, and as the weather rises to a pitch of ferocity, all of Malcolm's certainties are torn asunder. Finding himself linked to a baby by the name of Lyra, Malcolm is forced to undertake the challenge of his life and to make a dangerous journey that will change him and Lyra for ever...