From the introduction:
The Last Supper must be played in a single session and incorporates a potluck supper. Each participant should bring one or more dishes, and they are encouraged to coordinate for a satisfying meal. The GM will provide the beverage.
One participant - the GM - takes the role of Christ. The remaining participants - the players - each play one of the twelve Apostles. Of these Apostles, some - the evangelists - will go on to write the Bible. Others - the proselytes - will travel unto the corners of the world and spread Christianity to the masses. And one - the traitor - will betray Christ to the Romans and initiate the crucifixion.
Without a traitor, all other efforts will fail.