In Monsieur (1975), Durrell introduced the pre-WW II chateau of Tu Duc, at Avignon in Provence--where the owners, sisters Livia and Constance, entertain an odd, international array of thematically weighted house-guests. Then, in Livia (1979), the focus lingered on the far less agreeable of the two sisters--a budding Nazi. And now, in the third novel of Durrell's projected ""quincunx,"" with the war fully under way, good sister Constance receives the most attention--though again there's a smoky assortment of free-floating plot pieces and vignettes. The quest for treasures of the Knights Templar continues. Exotic, jagged chunks of sheer literary sensibility pop up here and there without real pattern. Some episodes, straining for historical resonance, are merely foolish and trite--as when a German officer (Avignon is now occupied by the Vichy fascist militia and the Germans) takes advantage of his Polish maid: ""She was his, she submitted, and the thought excited his cupidity; he overwhelmed her as his army would soon overwhelm her country and people, raping it, wading in its blood."" But Constance--a Swiss-trained psychoanalyst who returns to Tu Duc after her husband is killed in Egypt by his own English troops (a terrible error)--is a somewhat more rewarding central focus than was the flashier Livia. And when Constance develops an intense philosopho-erotic love affair with an Egyptian named Affad, Durrell has the opportunity to show off his undeniable talent for tackling sex in a slightly mad fashion: energized by Affad's jaunty sex-chat (""conscious orgasm,"" healthy sperm, women's thighs as ""the tuning-fork of male intuition""), the Constance/Affad section is very odd yet quite exquisite. Like Livia, then, most of this third installment is too fussy and eccentric to attract those who aren't already devoted Durrell-ians; but there are piquant sequences here that will interest all connoisseurs of offbeat sexual sensibilities.