The demon

"In this story, Jason Blood travels to Cornwall, U.K., to find the spirit of Merlin and lift the curse that binds him to Etrigan the Demon. But a clue leads Blood to the British Museum, where a mystic book may hold the key to his freedom. But unraveling a centuries old curse is anything but easy, and in the course of his struggles, Blood learns more about his mystical alter ego than he could have imagined. Collects THE DEMON miniseries #1-4 and issue #22 of the monthly series that followed it"--