Astrobiologist, rancher and Vietnam veteran Jim Johnson now works as a special government agent with his long time friend Brush, attached to a biological counterterrorist group. They have had several difficult missions over many years, which they have carried out in their own very individual way. Returning from one of these, they are both looking forward to a llama-packing trip, with friends, in the Pasayten Wilderness, northeast of Seattle on the Canadian border. Their idyllic time is cut short, however, as they are recalled to deal with a possible terrorist threat. A bacteria resistant to all known antibiotics has been set loose in the University of Washington medical school. How can its deadly spread be stopped and what is the connection with the deaths of some horse packers in the Pasayten Wilderness and a mysterious group of Middle Easterners?