While an Army Ranger, Jim Ellison spent 18 months alone in the jungles of Peru. This had the result of heightening his senses. He now has the ability to see, hear, touch, smell and taste better than anyone else.
Working as a detective in the Cascade Police Department, he is aided by Blair Sandburg, an anthropology student who had made of study of "Sentinels" - warriors/guardians with heightened senses.