“I start with zero. Nobody dies today.”

The strange note delivered to Detective Lieutenant Rick Peller of the Howard County, Maryland, police was just the beginning. Soon Peller is in hot pursuit of a cunning killer basing murders on the Fibonacci series, a mathematical sequence in which each number is the sum of the preceding two. And the only thing Peller knows for sure is that the series never ends.

As the murders pile up, Peller, his police colleagues Detective Sergeants Corina Montufar and Eric Dumas, and consulting mathematician Tomio Kaneko race against time to identify and capture the killer. Nor is murder their only problem. The public, the press, and county officials demand that police apprehend a golf-club wielding mugger terrorizing their community. Both crime sprees are wrapped in seemingly impenetrable mystery. Are mugger and murderer one and the same? Why does the murderer seem to know Peller? Why is the Pentagon eager to keep a lid on the investigation? And can the detectives find the killer before he commits his final, terrible crime?