The Grail of Sir Thomas

When Sir Thomas, a hero of Crusade, obtained the Holy Grail in hot Saracen sands, that was just a beginning of his dangerous and unpredictable quest. The way back to Britain, his homeland, lies across scorching deserts and the treacherous city of Constantinople. Assassins, villains, hirelings and blood-thirsty savages seem to be leaping onto his way from everywhere. Thomas is proficient with his long sword, he has a brave heart and valiant soul… and also a mysterious companion, a pilgrim from the far northern land of Kievan Rus' who came to the knight's aid for some own reasons. But is that enough to overcome the most powerful enemy he's ever clashed and deliver the priceless relic to where it belongs?