Quinx: Or, the Ripper’s Tale by Lawrence Durrell (Viking: $15.95; 201 pp.)

“Quinx,” as its title implies, is the fifth and final novel in a sequence that Lawrence Durrell has been building for the last 10 years, under the title “The Avignon Quintet.” The 73-year-old major British novelist and poet has written 27 books, the best known of which comprise “The Alexandria Quartet,” an ornate and stylish tetralogy first published between 1957 and 1960, and still widely read.

While the central characters of “The Avignon Quintet” persistently reappear--in “Monsieur” (1975), “Livia” (1979), “Constance” (1982), “Sebastian” (1984), and now “Quinx”--the five plots do not follow each other sequentially and may be read in any order. “Monsieur,” for instance, turns out to have been “written by” a character who first shows up in the later novel “Livia.” These fluctuating levels of fictional reality give Durrell’s novels a playful concentric pattern instead of a straight chronological order.

“The books would be roped together like climbers on a rock face, but they would all be independent,” as the writer Blanford explains in the second novel of the nonseries. “Quinx” is as good a place to start as any, particularly since Durrell places it schematically in the midst of the other four, as in the “quincunx” array on the five side of dice. The result, wherever we start or stop in our reading, is a prismatic, crystalline work that radiates rainbow perspectives on familiar events as they revolve before us.

Constance is a psychoanalyst; Blanford is the novelist who has loved her from a prudent distance for years. Sabine is a Gypsy fortune-teller. There are also a wealthy British lord in search of buried Crusader treasure, an Egyptian prince, and some double-agent spies left over from recent World War II. Their separate quests ultimately bring all the characters together at one spot: the Bridge of Avignon. Below its arches, in five connected caves, are said to be buried not only the Crusader riches, but also weapons from the recent Resistance (dangerously booby-trapped) and the ancient relics of a saint still held dear by the faithful Gypsies.

What happens? Like the Bridge which comes to an end in the river Rhone without reaching the far shore, Durrell teasingly suggests the outcome of his interwoven plots, without spelling it out all the way.

The novel promises a happy ending from its very start, though, and it does not disappoint. At its center unwinds a fully developed love story between two exceptionally mature and thoughtful individuals, through whom Durrell convincingly celebrates “the couple, the basic brick of understanding.”

In the classic tradition of Modernism, “Quinx” artfully probes art’s own underpinnings, while Durrell’s philosophic punning shows us just how close the cosmic and the comic are. “The riddle of the Quinx” yields itself up to what Durrell calls “love at first insight.” Seriousness and play are the happily wedded couple at the heart of “The Avignon Quintet,” a durable delight now aptly, zestfully complete.