Not So Long Ago or Far Away : LIVING UPSTAIRS, <i> By Joseph Hansen (Dutton: $20; 218 pp.)</i>

Joseph Hansen’s fans have mourned the passing of his Dave Brandstetter mysteries, those gems of graceful description and characterization that capture the idiosyncrasies of life in Southern California from a gay perspective. We can always hope that Hansen will be moved to devise a way of bringing Brandstetter back, but in the meantime there’s consolation in the form of his new novel, “Living Upstairs,” which could just lead to a new series.

With its unexpected twist at the finish and a mysterious death at the beginning, the novel can be considered a mystery, but it’s really about what it was like to be gay, poor, in love and living in Hollywood 50 years ago.

Hansen’s hero--and possibly, alter ego--is 20-year-old Nathan Reed, who works in a Hollywood Boulevard bookstore and has just fallen in love with Hoyt Stubblefield, a gifted young painter who is something of a mystery man. He may be a communist or a government agent spying on communists. In either case, the author, who turned 20 himself in 1943, plays down Hoyt’s activities to evoke with gentleness and humor both the joys and heart-tugs of a passionate first love and the Los Angeles of World War II.

If your own personal history coincides at all with Hansen’s world, you can savor the accuracy with which he brings to life not only Hollywood but a considerable portion of Los Angeles when it was a beautiful, smog-free, safe place to live--although at times it could be dangerous for gays, as Hansen makes clear. Natives and long-time residents can appreciate Hansen’s eye for authentic details: eating at an Owl Drug store counter, drinking Acme beer, going to the Admiral (now Vine) Theater on Hollywood Blvd, boarding a red car for a dime. (But wasn’t the fare a nickel until sometime after the war? . . . These are the gentle pleasures in store for readers of “Living Upstairs.”)

Then as now (but surely less sinister in the past!) Hollywood was a haven for colorful characters, eccentrics, movie has-beens, Bohemians and struggling creative types. Several of the people in Nathan and Hoyt’s circle of friends, neighbors and acquaintances are clearly drawn from actual people. Boozy but elegant Gentleman Jim Hawker, described as a Great American Novelist, seems mighty like William Faulkner; among the real people referred to in passing is veteran character actor Grady Sutton. The people in “Living Upstairs” recall those in “The Day of the Locust”--and Nathanael West, in fact, is mentioned.

As with all of Hansen’s books, “Living Upstairs” is beautifully crafted, perceptive and compassionate in its view of human nature, honest in its emotions but discreet in its depiction of sex. There are shadows, even sadness and loss, but they serve to underline what is a sunny, joyous recollection of youth in a place much changed and a time long gone.