Carnage - Maxime Chattam

When a massacre takes place in a Harlem school, Lamar, A New York detective for twelve years, is called to the scene. A student, aged seventeen, has shot everyone in his path before shooting himself. Having collected all the evidence, Lamar reconstructs the blood-soaked morning of the killer. Ten days later, a second massacre occurs at a school in Queens. Once more, a student kills multiple victims before turning the gun on himself. A new massacre occurs elsewhere. Three sets of killings in three weeks, all the same with the perpetrators committing suicide. It isn't just a coincidence -