This story beings on a windy spring day in the Chilterns when the calm, organized life of Joe Rose is shattered by a ballooning accident. The afternoon, Rose reflected, 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 take desperate measures to stay alive.