One windy spring day in the Chilterns, Joe Rose’s calm, organised life is shattered by a ballooning accident. The afternoon, Joe reflects, could have ended in mere tragedy, but for his brief meeting with Jed Perry. Unknown to Rose, something passes between them – something that gives birth in Perry to an obsession so powerful that it will test to the limit Rose’s beloved scientific rationalism, threaten the love of his wife Clarissa, and drive him to the brink of murder and madness.