A ‘40s Coming of Age : A teen-ager confronts and accepts his sexual orientation : JACK OF HEARTS <i> By Joseph Hansen (Dutton: $19.95; 214 pp.) </i>

When Joseph Hansen’s “Living Upstairs” was published in late 1993, fans who mourned the passing of his Dave Branstetter private-eye series were cheered by this novel, which introduced us to 20-year-old struggling writer Nathan Reed, who was in the throes of a first love while living in side-street Hollywood in 1943. The hope that we would meet Reed once again has been fulfilled with “Jack of Hearts,” which presents a 17-year-old Nathan who in the course of the novel confronts and accepts his sexual orientation in the summer of 1941, just as the United States is heading irrevocably toward involvement in World War II.

Like “Living Upstairs,” “Jack of Hearts” also has a mystery but it is similarly peripheral yet significant politically. The Dave Branstetter books, whose hero is a tenacious, courageous, middle-aged gay insurance investigator, were always much more than mysteries, offering a wise understanding of human nature from a mature gay point of view. “Jack of Hearts” and “Living Upstairs,” however, seem so personal that they read like coming-of-age memoirs.

“Jack of Hearts” finds Nathan living with his seriously impoverished but loving parents in a crumbling, large Victorian house that had belonged to a relative. The town is “Fair Oaks,” and it sounds mighty like South Pasadena or perhaps another community in the area. Hansen evokes time and place with the kind of fidelity and acuteness of eye and ear that he brought to the Hollywood of “Living Upstairs.” You don’t have to be the same age as Hansen, born in 1923, although you probably have to have been at least in kindergarten by the time of Pearl Harbor to appreciate fully how accurately he evokes a vanished Southern California life where even the humblest neighborhoods were attractive--and safe. It was an era when people really did seem to have more time for each other.

The love depicted between mother and father, parents and child, is so unselfish and tender that its quality is piercing--and renders all the more poignant Nathan’s eventual realization that they will never be able to deal with his sexual orientation. Throughout this slim volume you’re left wondering how people manage to be so thoughtful of each other; Nathan’s burning desire to be a playwright--a new little theater group wants to stage his promising first effort--never interferes with his concern for his parents, his fortunetelling mother and his chronically unemployed musician father or, for that matter, his increasing number of friends.

There’s a terrific tug of nostalgia in “Jack of Hearts,” but as before Hansen reminds us just how dangerous those times could be for gay people--and by extension, all minorities. For all its sunniness and warm sentiments, “Jack of Hearts” is especially effective in the way in which the larger world, one in the process of being engulfed in war, gradually intrudes upon bucolic Fair Oaks.