The final two Demon Prince novels (The Demon Princes, Vol. I, p 342) originally appeared after an excruciating 12-year hiatus during which even the most committed fans despaired of grandmaster Vance ever completing the series. The Face (1979) features Lens Larque, the ugly, malevolent, obsessed trickster whose motivations avenging hero Kirth Gersen comes to share. And in The Book of Dreams (1981), Gersen pursues the vindictive, megalomaniac Howard Alan Treesong's weird multiple personalities. Readers will also discover, among other things, the fate of the stalwart Marmaduke in ``Scroll from the Ninth Dimension,'' a typical bit of Vancian seriocomic brilliance. Nonpareil.