TALES OF THE CITY MORE TALES OF THE CITY FURTHER TALES OF THE CITY BABYCAKES SIGNIFICANT OTHERS<i> by Armistead Maupin (Harper & Row: $10.95, each)</i>

Bedtime stories for Baby Boomers. Armistead Maupin’s continuing saga of life in San Francisco began as a serial in the Chronicle in 1976, and his tongue-in-cheek depiction of the late ‘70s sex-and-drugs singles scene seems as remote today as the misadventures of the Pickwickians.

Although the search for love and security in an increasingly uncertain world remains at the heart of this popular series, the tone has darkened. The three earlier books played relatively down-to-earth characters against such extravagantly silly plot twists as the discovery of the Episcopal Cannibal Cult in “More Tales.” But as the liberated ‘70s gave way to the grayer, grimmer ‘80s, Maupin grew more serious. He began to confront the AIDS crisis in “Babycakes,” which features his most sensitive writing; the threat of the pandemic and the responses it engenders dominate “Significant Others.”

Maupin also has lost interest in Mary Ann Singleton: The sweetly bewildered ingenue from Cleveland who was the main character of the first books has become a materialistic, upscale yuppie. The focus of the story has shifted to her husband, Brian Hawkins (once the archetypal stud on the prowl, now a doting father), and to her gay confidant, Michael Tolliver, who struggles to cope with the death of his lover and his own HIV+ status.

Maupin’s clean, readable style, broad sense of humor and flair for dialogue that rings absolutely true make these novels as difficult to put down as a dish of pistachios. The reader starts playing the old childhood game of “Just one more chapter and I’ll turn out the light,” only to look up and discover it’s after midnight.