PROLOGUE FRIDAY, APRIL 23 OXFORD, ENGLAND ATHENA RAN BLINDLY down the dark country lane, her breath coming in short, harsh gasps. Her school jacket with the St. Polycarp’s logo sewn on the pocket was no protection against the sudden drenching spring rain. The knapsack strapped to her body impeded her flight. It did not occur to her to discard it. As the bewildering shock began to wear off, she desperately told herself she was