Life is suddenly very busy for forensic examiner, Jack McCain. He's just left the crime scene of a murdered scientist - suspected lethal factor: anthrax - when his boss calls, asking Jack to head up the department for a while. And there's also the matter of a dead nun which Jack needs to look into; Sister Gertrude has lived quietly in a secluded convent since early adulthood, so she can't have had much chance to offend anyone. Could her murder relate to her Croatian background? And what is the meaning of the carved symbol on the slain nun's leg? Before Jack has much time to ponder the answers to these questions, the scientific community is rocked by another anthrax murder. Who but another scientist could procure or manufacture anthrax? Why are scientists being targeted? Who will be next?