Webb makes an urgent call to Harm at home one night, then his cellphone dies. The next morning the admiral announces the discovery of Webb's body after an explosion the night before. Surprises abound. Harm seeks and finds explanations.

A US submarine experiences a series of mishaps and illnesses. Harm and Mac investigate while at sea; they suspect that someone aboard has induced the problems. Harm figures it out, and the bad guy tries but fails to put them out of his way.