Doomsday BookFor Kivrin Engle, preparing an on site study of one of the deadliest eras in humanity's history was as simple as receiving inoculations against the diseases of the fourteenth century and inventing an alibi for a woman travelling alone. For her instructors in the twenty first century, it meant painstaking calculations and careful monitoring of the rendezvous location where Kivrin would be received. But a crisis strangely linking past and future strands