As much as I enjoyed the subsequent two novels of the Von Bek trilogy (_City in the Autumn Stars_ and The Dream Thief's Daughter_) this first volume is still my favorite. It could easily have stood on it's own as a classic.
The basic premise is that Lucifer is not an all-knowing, all-powerful arch fiend, but merely a frustrated, desperate exile. God exiled Lucifer to earth with no instructions and no further communication. In his own words, Lucifer tells how everything that he did since then was his own idea, done on his own initiative. First, he tried to prove that he could build a world that was greater than the Creator's (he reveals that most of the world's rulers and churchmen are really "his".) However, by the 17th century, Europe is clearly dieing in unending warfare and plague INSPITE of his efforts to make a better world. Lucifer admits that his efforts have been a colossal failure and that he has no idea why. Moreover, he just wants to reconcile with God and go back home to his old position in heaven.
In desperation Lucifer sends an agent to find the Holy Grail. Grasping at straws, he believes that the legendary Grail will grant immediate union with God, and as a result the Last Judgement and an end to the World's Pain. Unfortunately, the Devil has no pure knights to search for this Grail- the closest thing he can find is Capt. Ulrich Von Bek. Von Bek is far from innocent, since as a mercenary soldier he has wilfully commited murder, torture, rape, and robbery as "part of the soldier's craft." Von Bek does have a conscience, though- he just gambled that there was no God or Devil to answer to for his crimes.
Von Bek goes forth on this hopeless quest- quite convinced that Lucifer, and quite possibly God, are both out of their minds....