By Robert Parker

Putnam. 256 pp. $18.95

THE REAL SECRET of a good detective series is not plot. It's character. We love our detective heroes less for their brilliance or toughness than for their rough edges and eccentricities, for the way they talk and the way they think. Nero Wolfe, Philip Marlowe, Travis McGee, Lew Archer and Kinsey Milhone have all won loyalists because they're folks we want to spend time with. We miss them when they're not around.

And so it is with Robert B. Parker's Spenser, the yuppie-as-tough-guy who spends some of his time detecting and much more time eating, cooking, drinking, romancing his beloved Susan Silverman, and offering knowing wisecracks. For Spenser's loyal fans -- I'm one -- a bad Spenser book is better than no Spenser book at all. And a good Spenser book is a cause for celebration.

Stardust is better than most. Parker seems to have profited from the sabbatical he took from Spenser to complete Poodle Springs, a Philip Marlowe story that Raymond Chandler left unfinished at the time of his death. Trying to catch Chandler's style precisely took discipline, and Parker carries some of the lessons over into his new Spenser novel. The plot isn't quite up to Playmates, the last Spenser book, but Stardust is, as Nero Wolfe would put it, very satisfactory. It confirms Parker's comeback from the lean times of a few books ago.

There are a lot of nice descriptions of Spenser's Boston stomping grounds. There are also the classic Parker/Spenser asides that suggest we're all in on the same joke about how detective stories get written. At the end of a particularly clipped exchange with a suspect, Spenser offers this to his reader: "I felt like I was trapped in a Hemingway short story. If I got more cryptic, I wouldn't be able to talk at all."

In his self-conscious suggestions that he thinks of himself as a character inside a detective story, Spenser may be the world's first postmodern detective. Spenser himself takes a crack at defining what a "post-modern statement" is when he describes a house that "looked like it had been designed by Georges Braque while drunk . . . it flaunted itself against the pastured landscape in self-satisfied excess."

Spenser books are full of self-satisfied excess -- intellectual asides designed to make Spenser and the reader feel smart; great lovemaking with Susan Silverman, the shrink to whom Spenser is unswervingly faithful; and one good low cholesterol meal after another. (The best one in this book is "duck breast sliced on the diagonal and served rare, onion marmalade, brown rice, broccoli tossed with a spoonful of sesame tahini.")

Between the meals, there is a plot. It's about a nymphomaniac television star ("The face says I'm an angel, and the body says, The hell I am") who is getting threatening phone calls. Spenser is hired to guard her, and he and Suze decide -- they always do this for people -- to save her from her inner demons. Hawk, Spenser's sensationally tough black buddy, makes his appearance, and he and Spenser engage in their usual knowing banter about how blacks and whites view each other.

There's enough action to keep you going. Among other things, Spenser gets out to San Diego and Los Angeles and encounters a Hispanic mobster who talks like he went to Harvard Business School. But the action isn't the point. As Spenser somewhat wearily explains, there isn't really all that much to a good detective story. " 'You start looking,' I said, 'and you ask people things, and then that leads you to somebody else and you ask them and they tell you something that hooks you onto somebody, and so on.' " You stick with Spenser because he's fun to listen to; and besides, the food is great, Suze is lovely and Hawk is a kick. STILL, A specter is haunting Spenser and it's the specter of creeping smugness. Back in the 1970s and early 1980s, in the heyday of the series, life for Spenser was a struggle. It took him several books and much pain finally to nail down his idyllic relationship with Susan Silverman. Now, they are settled in for the long haul, examining the world with a certain detachment, convinced to the point of arrogance that their values are the right values. Anyone who shared in Spenser's troubles is certainly happy for him and Suze. But their moralistic psychological discourses on other people's craziness are getting a little tiresome. They make you realize why Massachusetts liberals have a tough time winning elections.

Robert B. Parker created Spenser and got him through the tough times of the '80s, and that's probably all we can fairly ask of him. Nonetheless, Spenser's pride is that he is the world's most self-aware detective story character. He should be above his current smugness. Maybe he and Suze should have a baby. Now that would bring him squarely into the '90s.

E.J. Dionne Jr. is a reporter on the national desk of The Washington Post.