Ghostwalk

Cambridge, 2003: the son of a reclusive historian discovers his mother's body floating in the river. In her hand, she clutches an antique glass prism. The book she was writing, the story of Isaac Newton as an alchemist, remains unfinished. It looks as if the author's findings will go with her to the grave. The woman's friend, and her son's former lover, takes on the task of writing the missing chapter. But she soon finds herself entangled - with the son, with a series of unexpected seventeenth-century deaths, and a ghostly figure intent on sabotaging her work.