Tlingit Alaska State Trooper Robert Sable investigates a serial killer who uses stealth and carbon monoxide to kill alumni from the Chugach High School class of 2000 and their families. So far, all the deaths have been ruled accidental. It appears the killer is exacting revenge for bullying and abuse in high school. The killer leaves minimal evidence, only a tiny smiley face with the number 2000. Since Sable's wife is a 2000 graduate, she may be next on the killer's list. Sable and his team must catch the killer before he strikes again.