THE RETURN OF RAMON, the fourth and final novel of C.A. Rodrguez's Illusian Sequence, is by far the darkest and most ambiguous work of this brilliant series. Like the three previous books in the Sequence RASHINGOR, ST. PETER'S WOOD AND THE STREET OF SECRETS it takes off from a classic genre, in this case the thriller, and employs with enormous adroitness a style appropriate to that form. The swift, compelling plot then follows the steps of an aging night-shift waitress in a lonely diner who is alternately stalked and lured by a darkly handsome, courtly-mannered customer who does not speak. All the familiar themes of the Sequence death, love as a compass, and the wonderful are here, explored with that exquisite care for language and image, that respect for character, that disarming narrative grace that characterize all the books, along with an exceptional intellectual complexity set forth as if without effort, lightly, and in the sweep of a great read.