Book Two in the Preacher series by Garth Ennis & Steve Dillon.
In the continuing saga of the bizarre adventures of faithless Texas preacher Jesse Custer, Jesse, along with his girlfriend Tulip, and their friend Cassidy, the Irish vampire, head west to a party of Babylonian proportions. Then, Jesse heads for France to rescue Cassidy from the clutches of religious fanatics. His search leads him into a no-holds-barred battle against the forces of the mysterious organisation known as The Grail. Also told here is the story of how Cassidy became a vampire in the first place.