When the Snow Falls or Fifty Fifty

Whenever a human life confronts an instance of fifty fifty probability, be it surviving or succumbing to injury, giving birth to a boy or a girl, passing or failing a test, the universe bifurcates, and two lives run on in parallel, one for each outcome - neither aware of the existence of the other. This fascinating premise is the key to the mystery of how Rob and Bobby find themselves able to step into and out of each other's disconcertingly similar but different worlds, using a snow storm paperweight as a vehicle. But what might happen if the vehicle gets broken? The book's two endings explore the possibilities. This is one of the most thought-provoking books I've read in a long time. It touches upon a metaphysical enigma at just the right level for curious children, while the tale of bereavement, acceptance and renewal that it tells is both moving and intriguing.