RALPH NADER combines two qualities that make him singularly fearsome: the wonderment of a detached observer and the street smarts of a savvy private eye. The first quality leads him to ask interesting questions. The second equips him to root out the answers.

Indefatigable and uncompromising after all these years, Nader now has gone to work on nine high-powered moguls and the businesses they dominate. The result, reliably Naderesque, is part investigation, part lecture, and part unorthodox study of power atop the heap.

Nader doesn't give much for the distinction between public and private power holders. He lumps them all into a corporate/political management class that he stubbornly holds accountable for the public welfare. So he sets out with a broader point of view than others might have, a willingness to ask provocative questions and disdain the secrecy and proprietary silence too often tolerated from the private sector. He and co-author William Taylor thus produce an informative and thoughtful work but one that is also dry and unsatisfying.

Most interesting, perhaps, is the effect gained by studying nine men in widely different fields: David Roderick of U.S. Steel, Roger Smith of General Motors, Paul Oreffice of Dow Chemical, Felix Rohatyn of Lazard Fre res, Whitney MacMillan of Cargill, Thomas Jones of Northrop, William McGowan of MCI, William Norris of Control Data, and Charls Walker, a tax lobbyist. The nine, all men, were chosen from a longer list of potential subjects to reflect regional, corporate and individual diversity. And they provide a pretty good aggregate model of the big-time honcho. Even allowing for differing individual styles, most of these men seem bold, self-possessed and driven -- zealously devoted to their own agendas and unhesitating about imposing those agendas on others.

"If I owned a business," says union leader Mike Ally about the head of U.S. Steel, "I would want David Roderick to be chairman of the board . . . He's not afraid to make decisions. And he's ruthless and conniving. That's what you need if you own a very big business. Those are the kind of people who succeed."

In their effort to "broaden the public appraisal" of these men, the authors do exhaustive research. For Control Data's Norris, for example, they interviewed 90 people (including Norris twice) and cite 106 published sources, 14 government documents, nine corporate records, and an unpublished court file obtained under the Freedom of Information Act. This digging nets a few chewy (if not always new) nuggets, such as internal memos by John DeLorean alleging irresponsibility at General Motors or Watergate-era memos detailing Northrop's Thomas Jones' illicit gifts to the Nixon administration. But this mass of information doesn't translate into insight. The work, though thorough, is surprisingly disembodied and lacking in synthesis. INTRIGUING questions are left dangling. Why do some leaders succeed and others, with apparently similar qualities, flop? How is power wielded day-by-day within a conglomerate? In what ways does a leader's personal style trickle into the nooks and crannies of his institution? What is corporate social responsibility? Most disappointing is the lack of rich detail and anecdote. The book yields little sense of the personal quirks and peculiar routines that insiders observe under a charismatic leader. The authors remain outsiders, poking at the edges, straining to peep in. Yet I am drawn to the book, because of Nader's earnest persistence in raising corporate responsibility issues.

Who else would write about banker Felix Rohatyn: "the question arises as to why Rohatyn is so comfortable coasting. He understands that we are living in a period where criticisms of greed, speculation, or financial short-sightedness have become unfashionable, a period when, in terms of economic power, anything goes . . . Such a period makes it all the more urgent that Rohatyn risk some of his inventory of trust and friendship to act more vigorously on his views."

Who else would urge AT&T competitor William McGowan of MCI to "wake up one morning" and ask himself, "Why can't I open new doors for millions of Americans to communicate with one another for community purposes, for agendas of social betterment, and for a general right of access to the new telecommunications and computer networks? Why can't I use this new technology to shift the balance of power away from the Big Boys to the ordinary citizens of this country?"

Judging this kind of book is like appraising a leap off the high dive: You have to consider the degree of difficulty. In taking on the Big Boys, Nader may hit the water at an oblique angle. But he earns respect for the audacity of his effort.

Carl Sessions Stepp, a former reporter and editor with The Charlotte Observer, teaches journalism at the University of Maryland.