Head cases : a novel

FBI Agent Gardner Camden is an analytical genius with an affinity for puzzles. A serial killer from one of Gardner's solved cases, presumed to be dead for over a decade, is found murdered, and then soon after, another body with a similar story. The mastermind murderer has left clues and riddles for Gardner and his team - a mathematician, a sniper and weapons expert, a computer analytics specialist, and their leader, a career agent - as they track him across the country.