Twelve-year-old Alex Revelstoke is different. He can see disease. Also injury, illness, and anything else wrong with the body. This comes in handy when a classmate chokes on a hot dog or when the janitor suffers a heart attack unclogging a gooey science experiment gone awry. But Alex soon learns his new ability puts him and an unsuspecting world in peril. Throughout time, Revelstokes have waged a battle against ancient evil itself. A man, a being, an essence--the creator of disease. Alex has seen its darkness. He has felt its strength. He does not want to fight. But Alex is the last Revelstoke. The war has just begun.