Alright, so, the grail in this book is your typical cup that can give you eternal life and heal all wounds, but what's cool about it is that 3 different celestial factions play a giant cosmic game involving the grail, where they each use mortal pawns to go on a grail quest. Each grail quest is considered a round in their game, and can take hundreds of years per round. The factions are somewhat biblical, being heaven (god), "neutral" angels, and hell (demons, the devil), but he (the author) adds an interesting sci-fi twist to the whole story (this is, in fact, an inter-stellar time/space traveling type story). I think this would be a fun idea to work off of. We could undoubtedly remove the religious connotations and all that, but I do like the idea of all-powerful beings using mortal pawns to play a "grail quest" game. Naturally, they pit the pawns against each other, and may the best team win.