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