On January 20, 1942, in a grand villa on the shore of Berlin’s Lake Wannsee, a conference of Nazi officers produced a paper known as the "Wannsee Protocol," which laid the groundwork for a "final solution to the Jewish Question."

This Protocol has always mystified us. How should we understand this calm, business-like discussion of holocaust? And why was the meeting necessary? Hundreds of thousands of Jews had already been shot by squads in Russia or gassed in the camp at Chelmno.

Mark Roseman seeks to unravel this double mystery and explain how it was that on a snowy day, fifteen well-educated young men met to talk mass murder.