THE SEARCH FOR THE REAL NANCY REAGAN by Frances Spatz Leighton (Macmillan: $18.95; 406 pp.)

So how does one “search” for Nancy Reagan? One could follow Frances Spatz Leighton’s example--and just jump down the nearest rabbit hole.

How else to arrive in the extraordinary wonderland that Leighton creates--filled with images of imaginary Angst, miles of mistaken identities and sufficient sugar-plum sweetness to qualify it for an entirely new type of book. This is not psychohistory, but psychic biography.

In “Make-Believe: The Story of Nancy and Ronald Reagan,” Laurence Leamer did a great job in piecing together interviews with already published information and creating an interesting, provocative whole. Leighton has obviously misread the title of Leamer’s book--instead of make-believe, we have make-it-up.

How else could we read these sentences: “Nancy had many a surprise and a laugh . . . Nancy made what she considered a reasonable suggestion . . . Nancy looked and was really dismayed.” How does Leighton know these things? No dummy she, Nancy Reagan was smart enough to refuse any interviews with the author, but that certainly didn’t stop Leighton.

After the first few dozen pages, I wished I had the mind-reading powers that Leighton possesses. Then I could have figured out simple things: Does Leighton like Nancy Reagan, does she have any theme to this book and, if she found Nancy in her search, would she know what to do with her? But read on, I did, a victim of the point-of-no-return syndrome experienced when one reads a terrible book, that compulsion to finish each page as a matter of Spartan pride. So, just as the wolf of wonderment had almost gnawed its way into the sinews of my sensibility, there came two passages that were indeed gifts from the gods. Indeed, in every clouded biography there are silver sentences:

“Perhaps Queen Elizabeth did not realize how special she was. Only a few people were ever invited to the ranch. . . . “ Now if that doesn’t leave you loopy, read it again.

Then move on to my very favorite. This passage reflects Leighton’s ability (admittedly without benefit of any interviews) to know the First Lady’s deepest feelings, and she combines that supernatural skill with a strange sycophantic style:

“And it didn’t help Nancy’s nerves that the press was using models of colons to show the public exactly what was happening to Ronnie’s guts--was there to be no privacy, even about one’s colon?”

Leighton scrambles people and places with the joyous abandon of a Mad Hatter hostess who’s lost her seating chart. The Herald-Examiner’s former Wanda McDaniel becomes “The Washington Post’s Wanda McDaniel.” Bel-Air’s John Thomas Dye School becomes the Thomas Dye School.

But really, does it matter? Her disdain for detail, her delightful naivete is seen best in the way she explains away former White House aide Michael Deaver’s dilemma. Deaver is being investigated for not waiting the mandated year between leaving the White House and lobbying on Canada’s acid rain problem. “Of course, there was a good side. It was a worthy cause and the United States had agreed to cooperate in combating acid-rain pollution and sharing the cost.”

But nothing is more gloriously gauche than Leighton’s outrage at the fact that the wife of a public official can be put under scrutiny (and this from someone whose book will be serialized in the National Inquirer):

“And Nancy had been the whipping girl “ (without a doubt, emphasis hers). Even better, “Poor Jerry Zipkin, who was such a connoisseur of excellence and had helped her so much in separating good from poor taste, was dismissed by Time magazine as simply a ‘full-time partygoer.’ ”

But wait, you ask, did I like the book?

No, not really, but I admire the book’s author. This is courage unseen in Washington, D.C., in decades. Leighton has taken a well-perused clippings file and turned it into 400-plus pages of prose. Send this woman to New Jersey. She knows what to do with journalistic toxic waste.

Leighton predicts that after the end of the Reagans’ White House years, “Nancy will no doubt go back to lunching with The Group at Chasen’s in Beverly Hills.” That will be a good trick since Chasen’s has never served lunch and when last seen was alive and well and living in West Hollywood.