HarperBusiness, 284 pages, $25

Look past the foreword by noisy ex-GOP operative Mary Matalin. Forget that Unbridled Power is, at its core, a nuts-and-bolts tale of the federal bureaucracy published by a sober purveyor of management-theory tomes. And ignore—though that’s easier said than done—Davis’ annoying tone of self-righteousness. Despite these hazards, Power rises above the self-indulgent-whistle-blower genre. The book is politically evenhanded—and it’s a rollicking good read.

Consider some of the tidbits Davis uncovered during her seven-year tenure as the Internal Revenue Service’s first, and last, in-house historian:

•The agency still cites strict privacy rules to justify its refusal to release a tax-refund letter sent to the estate of Abraham Lincoln over a century ago.

•“Souvenir hunters” have apparently stolen the signature boxes from every presidential tax return in the IRS’s possession.

•The agency’s ill-conceived disposal of an odd metal box in its basement nearly resulted in a the dumping of a large amount of liquid mercury into Washington’s sewer system. Luckily, the mercury was cleaned up, at a cost of $175,000. The box had been lying there since before the Bureau of Alcohol, Tobacco and Firearms had moved out of the space 22 years earlier.

•At one point years ago an IRS commissioner asked a subordinate to locate pictures of ex-commissioners so they could be displayed in an IRS hallway. Failing to find any pictures in the agency’s own collection, the employee, according to legend, decided to purchase a number of secondhand photographs of 19th-century men, figuring no one would know one muttonchopped individual from the next. Years later, Davis’ inspection confirmed that many of the photos were not of the men they were supposed to depict.

And those are just the minor anecdotes. Davis’ big-picture stuff is just as intriguing. Consider her marquee claim: that the IRS has not turned over any of its records to the National Archives since the days of Prohibition, and indeed may have shredded the bulk of them. (She fails to find a smoking gun, but the evidence she reports is damaging enough.) Or that despite billions of dollars and two decades of effort, tax returns are still processed using early-1960s computer technology. Or that the IRS, in Kafkaesque fashion, regularly exiles troublemakers to its bureaucratic equivalent of Siberia (including, eventually, Davis herself, who resigned in the face an investigation she describes as a sham designed to force her out).

Then there’s Watergate. Most Nixonian doings are old hat by now, but Davis tells an unfamiliar tale that’s a real page-turner. In those days, the agency maintained a secret enemies list much longer than the president’s own. Indeed, the IRS’s list predated the White House’s and boasted lesser criteria for “enemy” status—even, if one document is to be believed, attending rock concerts made one eligible. Davis discovered this after perusing a forgotten (but not yet shredded) hoard of documents hidden in a vault behind a curtain in an obscure IRS conference room.

Davis’ story features goons (the Special Services Staff, or SSS), a shadowy ringleader (creepy midlevel-bureaucrat-turned-rogue-Nixon-toady Paul Wright, who later vanished into the mist), and a small resistance (IRS commissioners Randolph Thrower and Donald Alexander, who were out of the SSS loop but sought to clamp down on its activities).

The Watergate stuff may be (relatively) ancient history, but Davis reports that an early-1990s survey commissioned by the IRS found that almost half of the agency’s executives admitted that they would use their position to intimidate personal enemies; more than half said they would ignore wrongdoing if they saw it.

And Davis hardly pulls punches with people still on the job. The result is colorful and engaging but often, to her discredit, gratuitously mean. One executive assistant whom she cites by name looked like “a matronly librarian.” Another named midlevel bureaucrat “seems dried out and stretched on a rack, mummified and buried alive.” And Mike Dolan, who later rose to deputy commissioner, is introduced grunting—”all three-hundred-odd pounds of him”—and grasping for another slice of pizza.

Understandably, the IRS is painting Davis as disgruntled and vengeful; in fact, Davis told me that IRS officials have, according to her sources, told reporters in off-the-record comments that she’s emotionally unstable. Still, for a politicized city, Davis’ crusade seems surprisingly nonpartisan, with excoriations of Nixon balanced by jabs at latter-day sins by the Clinton administration.

Before joining the IRS, Davis spent most of her career as an internal historian with the Air Force and the Defense Mapping Agency, which she says were infinitely easier to cope with than the IRS. The daughter of a “hyperliberal” University of Nebraska professor, Davis says she’s “a lifelong registered Democrat who’s now drifting,” in part because of Democratic inattention to her concerns. “This is not a book about politics, just about the inept bureaucrats who run the IRS,” she says. “It’s interesting that people want to play it up as a political book.”

For the moment, Davis says, improving the IRS could be as simple as making it comply with existing federal records-management laws and narrowing the privacy statute the IRS uses to keep all its internal records secret from the outside world.

In the longer term, she says, “the top tier of management has to go—the top 10 percent. I don’t think they could make the cultural shift. The rest of the IRS employees are hard-working, dedicated civil servants. But the top-tier executives are like the Wicked Witch. We need to throw a bucket of water on them so they’ll melt away.”

Perhaps the IRS’s biggest mistake was in underestimating the volatility of this particular historian. “What were they thinking?” she muses. “Don’t ever piss off a writer. You’re safer pissing off a computer programmer.”CP