I can only wonder why.

Masters offers up a lengthy, detailed, sometimes labored, appraisal of Eisner and his long climb to the top, from little rich boy on the Upper East Side to earnest young man working for ABC in TV development to a self-serving, power-building senior executive for Paramount and Disney.

She probes Eisner’s life more diligently than Eisner himself did in his bland 1998 autobiography (written with Tony Schwartz), “Work in Progress.” To her credit, Masters delivers an assembly of arcana that obviously was not easy to uncover.

Through hundreds of interviews, she reports some juicy tidbits about executives like Barry Diller, Jeffrey Katzenberg and Michael Ovitz, alongside items on stars including Madonna in “Dick Tracy” (“War-ren, I’m losing my hard-on.”), the Cindy Williams/Penny Marshall catfights on the set of “Laverne and Shirley” and the disputes between Debra Winger and Shirley MacLaine on “Terms of Endearment.”

But the sum of these parts is less than scintillating.

Masters, who did much of the reporting for Time and Vanity Fair, is clearly proud of her discovery of an internal memo at Paramount in 1982, quoting Eisner: “We have no obligation to make history. We have no obligation to make art. We have no obligation to make a statement. To make money is our only objective.”

This very well may be the smoking gun that provides insight into Eisner’s soul.

But who cares?

Why should Eisner’s dedication to earning money be cause for denunciation? He is, after all, the chief executive officer of a major U.S. corporation and his allegiance is to shareholders.

This is probably the most problematic side to the book. Masters is determined to uncover anything she can about Eisner. But the fact is that he’s squeaky clean.

The revelations that show up are along the lines of Eisner’s game of hardball with actor Abe Vigoda, who declined to show up for a taping of the TV skein “Barney Miller.” In all his bluster, Eisner is quoted as saying: “We cannot fold to Abe Vigoda, it’s that simple.”

The most interesting reporting follows the relationship between USA chairman Barry Diller and Eisner, from the moment when Eisner was an assistant and Diller was a junior exec to the more recent power struggle.

No doubt Masters has strong relationships with these industry machers. She’s tight with DreamWorks founder Jeffrey Katzenberg, who emerges as her primary source.

The section on Katzenberg’s ultimate $ 270 million victory over Disney and Eisner was triumphant for “the dwarf,” as Eisner referred to him. And certainly the $ 90 million payday for Ovitz was a nightmare for the chairman.

But the picture of Eisner is out-of-focus. Try as she might, Masters is unable to paint Eisner in any other light than the Wonderful World of Disney spotlight he covets. And as the book comes out, he’s still going strong atop a resurgent corporate Mouse.

Disney No. 2, Frank Wells, who some say was the original subject of the book after his untimely death, gets lost in the shuffle. Wells is portayed more as a watchdog for Eisner than as the orchestrator (as many have said) of the Disney regeneration.

Even the cover art — a cutaway shot of Mickey Mouse, arms outstretched, with Eisner, Katzenberg and Michael Ovitz serving as mouth and ears — gives the impression of a cutesy tale about those in power at Disney.

If you’re looking for a tell-all Disney lambast, you’re better off with Carl Hiassen’s “Team Rodent: How Disney Devours the World,” which details the stormtrooper tactics the company used in its Florida ventures. “The Keys to the Kingdom” doesn’t explain why Eisner lost his grip. Instead, it shows why he’s retained it.