Former White House counsel John Dean has written another book about Richard Nixon. This one, “The Nixon Defense,” is based on new transcripts and promises new revelations. (Marvin Joseph/The Washington Post)

Forty years after Richard Nixon resigned in disgrace over the Watergate scandal, his former White House counsel, John W. Dean, who famously turned against the president, is back in Washington promoting his latest tome, “The Nixon Defense.” It is Dean’s third Watergate-related book since 1976.

What could possibly be new?

“I’ll show you the material I drew from,” Dean says, scrolling to a photo on his iPhone. “I was dealing with roughly 4 million words of new transcripts.”

The photograph shows 21 white plastic binders propped up in his office, forming a row more than five feet long, holding 1,000 hours of transcribed conversations captured by Nixon’s secret recording system. The material has been released periodically since Nixon’s death in 1994, and slowly brought to light by authors and scholars, but Dean says 600 conversations likely were never heard by anyone outside of the National Archives staff.

What’s it like to relive all that audacious scheming, profane mendacity and, some might argue, insanity?

Former presidential aide John Dean testifies for the second day before the Senate Watergate Investigating Committee on June 26, 1973. (James K. W. Atherton/The Washington Post)

“It’s bizarre,” Dean answers quickly. “The whole thing was bizarre then.”

Indeed. As Nixon himself said in one early taped discussion of the bungled June 17, 1972, Watergate break-in: “The whole thing is a strange bag.”

Listening to the tapes, for Dean, was like time-traveling, as he recalled his long-ago conversations with Nixon and top White House aides. He also heard what co-workers said in the Oval Office about him when he was absent.

In March 1973, for example, the president and his chief of staff, H.R. “Bob” Haldeman, speculated about whether Dean’s libido had something to do with his unflappable demeanor while trying to contain the scandal.

“I think he takes out all of his frustrations in just pure, raw, animal, unadulterated sex,” Haldeman says.

Nixon: “Is that right, is he quite a — ?”

Haldeman, talking over the president: “I guess he solves all his hang-ups that way.”

Dean’s reaction?

“I chuckled,” he says. “I’d never heard that stuff before.”

It’s still one of the most compelling political-corruption tales of all time. So many rogues, so many theatrics, so many people convicted of crimes — more than 30 in the administration or connected to Nixon’s reelection campaign. More sordid details than ever before are available in “The Nixon Defense,” a sort of director’s cut with bonus scenes (746 pages in all), which Dean says he wrote not for Watergate buffs but “for anyone who wanted knowledge of the record.”

Still slim and studious-looking more than four decades after his gripping revelations before the Senate Watergate Committee, Dean, 75, discusses his years of work on the tapes with a subdued, geeky enthusiasm. He explains how the National Archives supplied cassette copies of the original reel-to-reel recordings that proved central to Nixon’s downfall, how he digitized the material and sweetened the sound quality to decipher passages previous listeners had found unintelligible.

It was beyond tedious, he says, and the 37th president’s “obsessive-compulsive repetition” proved maddening. Whenever Nixon tries to distance himself from abuse of power and criminal conduct, “that’s when he starts spinning and twisting it, and bending it, and re-remembering it,” Dean says. “Not just once or twice, sometimes four or five times with the same person on the same day, and everybody has to sit there and listen because he’s the leader of the Western world.”

Nixon, on the tapes, even quibbles with his press secretary’s characterization of Watergate as a “third-rate burglary.”

“Breaking and entering and so forth, without accomplishing it, is not a hell of a lot of crime,” Nixon asserts. “It was a third-rate attempted burglary. That’s what it was. And it failed.”

Hearing all of this informed Dean’s understanding of Watergate “big time,” the author says.

“It’s a story that had to be told,” Dean says over a flatbread pizza and iced tea at a restaurant across from The Washington Post. “I was in a unique position to tell it.”

The lunch location summons forth some anecdotes from the tapes. It’s well known that Nixon hated The Post for its Watergate reporting. He banned its scribes from the White House.

But he also banned White House officials from going to The Post. In 1972, when the newspaper hosted a dedication ceremony for a new building, Nixon was “livid” to learn that then-Secretary of State William P. Rogers, once the paper’s lawyer, had accepted an invitation to speak, the tapes show. The president thereupon forbade Cabinet members from attending the event.

The historical value of Dean’s book — which unspools as a practically moment-by-moment chronicle of the White House machinations starting soon after the break-in — is one thing. The sheer entertainment value of the tapes he quotes is another.

The old gang’s all here, gabbing away in person or featured in the conversation-driven narrative. Naturally, it begins with the inept burglars — five mysterious Cuban Americans and former CIA men — nabbed at the Democratic National Committee headquarters in the Watergate office complex, carrying $100 bills, bugging devices and lock-picking tools.

“Well, it sounds like a comic opera, really,” Nixon says to Haldeman a few days after the caper.

“It really does,” Haldeman agrees. “It would make a funny goddamn movie.”

They proceed to envision a scene that could have been lifted from the script of the hit 1976 film “All the President’s Men.”

“I mean, you know, here’s these Cubans with their accents,” Nixon says, then begins laughing.

“Wearing these rubber gloves,” Haldeman interjects, “standing there in their expensive well-made business suits . . . and putting their hands up and shouting ‘Don’t shoot’ when the police come in.”

And as always with the Nixon tapes, it’s hard to stop once you get started.

“Well, who was the a--hole who did this thing?” the president queries Haldeman later about the break-in’s organizer. “Is it Liddy? Is that the fellow? He must be a little nuts.”

That would be tough-guy G. Gordon Liddy, the Nixon reelection committee lawyer, who served 41 / 2 years, the longest sentence of any Watergate figure. (Dean, who assisted prosecutors, got four months — or, as he likes to put it, “120 days.”)

At lunch, Dean examines a copy of “The Nixon Defense” almost lovingly. “You know, it’s the nicest book I’ve ever had,” he says, leafing through its bulk in search of a certain footnoted passage. “You notice the way it falls open? The whole tactile nature of the book, I was thrilled with what they did.”

Dean has been writing books and articles more or less nonstop since relocating from Washington to Beverly Hills in 1974 with his wife, Maureen, known as Mo. She became a celebrity in her own right during the hearings; they remain married. He has written eight books. Mo wrote a memoir and two Washington novels (steamy, reviewers said), the last one published 22 years ago.

Both also used to be stockbrokers; Mo, however, is a great stock-picker and handles the family investments, John Dean says.

These days, Dean schmoozes with people “in the industry,” he says, meaning Hollywood studio heads and actors, but he is circumspect about dropping names.

The Georgetown Law grad and former presidential counsel lost his law license because of Watergate and never sought to practice again. But he travels the country putting on a continuing-education ethics course for lawyers, drawing from the lessons of the scandal. Many of those snared in Watergate’s web of conspiracy, obstruction of justice and perjury were lawyers who had disabled their personal crime detectors.

In the new book, Dean writes: “No one doubted that breaking into and bugging the Democratic National Committee was against the law, yet no one, particularly [Nixon adviser John] Ehrlichman and myself, as lawyers, paused to examine that laws that come into force in a situation like that.” Dean plays the White House tapes as part of his ethics lectures.

Shouldn’t he have blown the whistle earlier? Dean joined the White House in 1970 and the dirty-tricks, spying and political-sabotage operations were well in force by 1971.

“I tried to leave the White House in September 1971,” Dean explains in the interview, but says he was told, essentially, that he would become unemployable, persona non grata, in Washington if he didn’t stick around for Nixon’s reelection campaign.

“I’m not claiming I did everything right. I didn’t,” he says. “But I sure as hell was not crazy like the others. Nor was I willing to lie for them.”

To this day, Dean becomes defensive when anyone suggests he went to “prison” for Watergate. No, he corrects, he served his time for obstruction of justice in a “safe house,” and routinely went to downtown offices to cooperate with Watergate prosecutors.

“I was the memory bank on Watergate,” he says.

In the White House, Dean considered himself “the desk officer for Watergate,” as he put it, keeping tabs on developments and making sure the president was up on everything.

Nixon appreciated his counsel’s buttoned-down diligence.

“I’m convinced that Dean is a real gem,” the president told Haldeman in that March 1973 chat.

“He’s a real cool cookie, isn’t he?” Haldeman says.

Nixon: “He might be cool, but he’s awfully smart.”

But after Dean told his White House superiors he would be cooperating with Watergate investigators, Nixon became especially vicious toward him. Dean should be slammed as “a traitor, a turncoat,” Nixon instructed his press secretary, Ron Ziegler. “It’s got to be done in a brutal slam-bang gut-fight way. You’ve got to draw the sword on him.”

But here it is all these years later, with Dean still standing — and writing — putting out into the world millions of words of conversations that his erstwhile boss fought so hard to keep secret.

In fairness, let’s give Richard Nixon the last say. It’s June 21, 1972, four days after the break-in, and coverage is escalating.

“I think the country doesn’t give much of a s--- about it,” Nixon tells Haldeman. “Most people around the country probably think this is routine, that everybody’s trying to bug everybody else, it’s politics.”

Perhaps he was right. But you know what people have been saying since Watergate. It’s not the third-rate attempted burglary that matters — it’s the monumental coverup.