Satan, in the form of a bewildered and naked Old Man, arrives in Brighton one dark and snowy December morning. That night a gull kills itself trying to get at Lucy Cuthman, a charity worker in her early 30s, through her bedroom window. A thick fog descends over the city - and lingers. The Old Man is twice attacked on the streets, before finding the squat where Geoffrey Cantor, our cultured and Byron-quoting narrator, lives. The Old Man discovers he has a mesmeric singing voice, and starts to busk around Brighton. He attracts the attention of Lucy, who is so diabolically enchanted that she can only see him as a beautiful young boy in need of help. In this guise, the Old Man visits her at work one evening - and promptly disappears. Hopelessly beguiled, Lucy searches everywhere for him. Meanwhile, mysterious bundles of money start turning up at her charity...