When I was growing up I always thought I'd make a good private eye. I was nosy enough; I still am. I had a mother who used to go through my sister's drawers, which I thought was an interesting habit - until she started going through mine and asking too many questions that I considered none of her business. Eventually the notion seemed childish. Jack Nicholson in Chinatown walking around with a sliced-up nose; who needs a sliced-up nose? If you need a detective, call the police. Several years ago, however, that notion was altered when a bilious and crusty-looking elderly Englishman, who in his youth had been married to an Astor, told me that his former in-laws and others like them (i.e., the very rich) used private eyes all the time. Detectives, he called them. And why?

"To spy on people, my dear boy! Why else?" he blurted out, impatient with my apparent naïveté."To find out what they can't find out!"

He did not say if the Astors had used private detectives on him, although judging from the tone of his voice, I could imagine that they had. Later my intuition was confirmed by someone who knew the ex-Astor husband well. What the spies discovered was not criminal, but it was certainly embarrassing, which for many law-abiding people, especially those in high-profile social circles, is worse than a crime.

Embarrassment is an important tool in the Private investigating business. Private Investigators are instruments of political power, a rich man's item. The secrets they are privy to are costly in more ways than one.

Their popular image is that of humorless men in gray suits with gray faces silhouetted by good key light. Movie actors. In reality, when private eyes are good, they're invisible. The payoff for them is the thrill of discovery.

Private eyes usually start out as cops or FBI agents, professions in which they learn tricks of the trade. Their business is mainly solving domestic mysteries on the order of "Do you know where your husband has been lately?" or corporate ones such as "Who has been looking into your attaché case?"

Sometimes the results are astonishing. A lawyer friend told me recently about a prominent executive in Los Angeles, a somewhat portly, distinguished-looking married man in his mid-fifties, who was receiving late-night phone calls on a private line which he used only for business. His dutiful wife, awakened and curious, pretended to sleep. The conversations would be short and monosyllabic, after which the man would rise from his bed, leave the room, leave the house, walk down to the end of the driveway and place an envelope in the mailbox. The third time this happened, instead of asking him what his odd behavior was all about, the wife went to see a private eye.

It was soon discovered that the husband was keeping a girlfriend, a pretty young thing of 21, in a comfortable apartment in Westwood. Except for the spate of quick late-night calls, they usually talked only once or twice a week by phone: Hi, Jill, how are you? Fine, Jack, and you? that sort of thing; nothing. He saw her only when he took a short business trip, which might be every few weeks or so. They would travel separately first class, always putting up in separate rooms in a luxury hotel. During the day, he tended to business, and she would shop till she dropped, at the best department stores and boutiques, with plastic and no limits, returning to her hotel with bags and boxes full of shoes, hats, dresses, coats, lingerie, jewelery and cosmetics.

In the evening, they'd go to a very early dinner at the best restaurants and then return to her room, where she'd order up champagne. Then for the next two or three hours they'd have a lively chat about her daily purchases, all monitored by the private eye, who'd bugged the room. But by midnight, the exec would call it a day, go back to his room, call his suspicious wife and turn in, while the girlfriend would go out dancing with people her own age.

This was the oddly ordinary routine. Then one day on a trip to Washington, the private eye noticed something unusual while watching his little shopper on a spree at Garfinkel's. She'd sometimes buy two of something, be it a little black dress or a pair of Chanel slingbacks; and always in two sizes: one very small and one very large. This observation was followed up that evening when, doubling as the waiter delivering champagne, the private eye gained entry to the girlfriend's room, only to discover the happy couple engaged in the grand old game of playing not house, but dress-up, wearing his and her dresses. The executive never suspected a thing until the wife served him with papers, armed with evidence that pointed not to adultery, but to something potentially more catastrophically embarrassing. Was it the girl, or was it the gown? A successful