Taking an in-depth look at those who say the Holocaust never happened, this text explores the motivations behind such claims. While most commentators have dismissed the Holocaust deniers as antisemitic neo-Nazi thugs who do not deserve a response, historians Michael Shermer and Alex Grobman have immersed themselves in the minds and culture of these Holocaust revisionists. They have conducted personal interviews with the deniers, read their literature, monitored their Web sites, attended their conferences, engaged them in debate, and even travelled around Europe to conduct research at the Nazi extermination camps. Uncovering a complex social movement, the authors go in deep not only to try and understand the motives of the Holocaust deniers, but also to refute their points one by one. In the process, they show how we can be certain that the Holocaust happened and, for that matter, how we can confirm any historical event.