From the back:
Jo Stoyte was a Hollywood multimillionaire, who owned movie studios, movie stars and a huge, moated, Gothic castle; he bought a Louis XV boudoir for His Baby, Virginia, daughter-mistress, concubine-child; he hung Rubens in the hall, Vermeer in the elevator– he had, in short, money enough to do all the glorious, monstrous things he could desire. All but one: He could not by eternal life, the prize he wanted most.
And then his physician, Dr. Obispo, discovered in an old manuscript evidence that eternal life was within Stoyte’s grasp. So they set out to look for the author of the manuscript, who if he was still alive, was over two hundred years old…