"I thought my kids would be horrified by the sex in my books. My daughter went, 'Ho hum, Dad' "

It is 7 a.m. in Chicago's superrich suburb of Northbrook. Inside one of the sprawling homes a writer in a striped caftan works behind a black-lacquered desk, his fingers tingling over the keys of an electric typewriter. "How do you say," puzzles Richard Himmel, "that someone was not trying to hide an erection?" The Mickey Mouse phone rings. "A client," Himmel sighs, then with hand clasped tightly over the mouthpiece, he confides, "I don't know how many houses I've done for her in the last 30 years—always in purple and yellow. The trick is to keep it from looking like an Easter egg."

That should be no problem for Himmel, who has deftly and triumphantly balanced two careers—he's Chicago's leading interior designer (with clients like Irv Kupcinet and Muhammad AM) and now a best-selling mystery writer. His latest, and most sophisticated, after 13 adventure pulps, is The Twenty-third Web, handled at Random House by Truman Capote's editor, no less. It is a thriller ostensibly about a young pro-Arab terrorist trying to undermine support for Israel by infiltrating the boardrooms—and bedrooms—of Chicago's Jewish elite. It's a bisexually tangled Web and has managed to offend quite a few Chicagoans, particularly those mentioned by name or insufficiently disguised. "In the end," smiles Himmel, "most of them were flattered, because I thought so highly of their sex lives." "Dick," says his longtime friend and literary agent Sterling Lord, "is a man who couldn't surprise me. He's a 56-year-old prodigy."

Born to the milieu he writes about (Himmel's father was a prosperous Chicago-based radio distributor), Himmel started out as a self-described "harassed intellectual." At the University of Chicago, he was editor of the Chicago Maroon in the golden days of President Robert Hutchins and philosopher Mortimer Adler. "Adler has the same terrible problem I do," says Himmel. "He's a scholar, but he wants to live like a rich Jewish entrepreneur."

Himmel studied philosophy for a time at his alma mater before World War II service as an Army buck private on Gen. George Patton's staff ("Can you imagine this effete fella working for Old Blood and Guts?" Dick marvels). Instead of returning to Plato and academe after the war, he decided to go to work for his sister Muriel Lubliner at her interior design store on the North Shore. Within months he was Chicago's and one of the country's most in-demand decorators.

"I'm really not an innovator," concedes Himmel, who designs everything from homes and restaurants to corporate jets and yachts. A classicist? Hardly. "I'm lousy on the Louies and worse on the Chinese," he admits, "but I'm damn good at getting on the bandwagon early. For example, I am the foremost bringer-inner of art deco in the country." Returning from Paris recently with a load of Lalique crystal, he unflinchingly paid an Air Canada freight bill of $19,000.

Himmel and Ellie, his wife of 31 years, share a taste for the eclectic. Their son John Maguire Himmel, named after the private eye hero of 11 Himmel paperbacks, and daughter Ellen are grown and have departed. But the Himmels' house, far from empty, is chockablock with modern art, French furniture and Chinese antiques. Even their fluffy white Pekinese, Seymour Irving, adds a decorator touch. "My kids said, 'Let's dye him red,' " to match a life-size cinnabar peke statue, recalls Himmel, "and I'm kind of sorry I never did."

Right now Himmel is polishing his next potboiler—this one set in Castro's Cuba. How does he come up with those sex scenes that are making him the Windy City's Irving Wallace and the terror of his Rolls-Royce set (he has two)? Himmel laughs: "The first lesson for a beginner is no matter what you make up, people have already done it."