A mysterious new contagion is decimating the population. It starts in the lungs, like the flu, then moves to the bones, where it weakens and breaks them, eventually killing the host. The disease's origin, methods of propagation and means of contraction are all unknown. There is no vaccine, and none is expected, as the virus is protean and elusive. If it remains unchecked and mutates into a more virulent form, it will become an extinction level event.