In 1960, when Thomas Mallon was in the fourth grade, he wore his Nixon-Lodge button to school and warned classmates that John Kennedy was too inexperienced to be president. Mallon was crushed when Richard Nixon lost, but things worked out well. He is a novelist for whom Nixon eventually provided interesting characters.

They’re back. Howard Hunt, Bernard Barker, James McCord, John Dean, Bob Haldeman, Fred LaRue, Gordon Liddy, John and Martha Mitchell, Jeb Magruder, Charles Colson, Herbert Kalmbach, Gordon Strachan, Rose Mary Woods, Anthony (“Tough Tony”) Ulasewicz and others. These were the dramatis personae of the scandal – actually a mare’s nest of scandals – that began to become public 40 years ago this coming June 17.

The gang that couldn’t burgle well properly got caught breaking back into the Democratic National Committee offices in the Watergate. This burglary was supposed to accomplish what a botched burglary in May had not accomplished: planting listening devices.

The characters all have an encore in Mallon’s novel “Watergate.” In his practiced hands – this is not his first fling at historical fiction – the festering mess of 1972-’74 becomes almost fun, actually funny, and instructive about how history can be knocked sideways by small mediocrities.

Mallon decided to put the minor figure of LaRue – a Mississippi moneyman for the Committee for the Re-election of the President – at the novel’s center after seeing a Watergate documentary in which LaRue was profoundly remorseful about not having spoken up in a March 30, 1972, meeting with Mitchell. There the former attorney general, then running Nixon’s re-election campaign, deferred for another day a decision about financing Liddy and other nitwits bent on mischief.

Mallon believes, and he thinks Nixon believed, that a distracted John Mitchell, who was deeply in love with his deeply disturbed and alcoholic Martha, was at least partly to blame for things spinning out of control. Be that as it may, Mallon uses his literary sensibility and mordant wit to give humanity to characters who in their confusions and delusions staggered across the national stage, utterly unqualified for the prominence they enjoyed until it devoured them.

A mountain of nonfiction has been written about Watergate, yet four decades later it is still unclear who ordered the burglary or why. Perhaps no one ordered it; perhaps Hunt and the Cubans from the Bay of Pigs Brigade 2506 thought they were supposed to improvise ways to help save the republic from President Nixon’s opponent, George McGovern, who was just five months away from losing 49 states.

Mallon thinks the burglars may have been seeking evidence that Fidel Castro was funneling money to the McGovern campaign. But having listened to hundreds of hours of Nixon’s tapes, Mallon considers them “totally inculpating”: He is sure Nixon – a “misanthrope in a flesh-presser’s profession” – did not know in advance about the burglary. Mallon hears Nixon on tape constantly “trying to give the impression that he knows more than he did, not less.” Mallon’s “Watergate” is a tale of floundering, frightened people unsure of what had happened or what others were telling investigators.

He says his novel contains “no big counterfactuals” – if you do not count his made-up affair between Pat Nixon and an old flame. The friendship he depicts between Nixon, he of “that madly dissociative smile,” and the acidic Alice Roosevelt Longworth was real. Mallon deftly suggests the continuities of American history when he depicts Longworth remembering Abraham Lincoln’s former private secretary, John Hay, when he was secretary of state for her father, Theodore Roosevelt.

Most Americans have no living memory of Watergate, and Mallon’s novel, which merits many readers, will be for many of them a primer, perhaps whetting their curiosity about this ugly discontinuity in the nation’s governance. Novels can be fine supplements to histories.

Dumas Malone’s six-volume biography of Thomas Jefferson and Robert V. Remini’s several books on Andrew Jackson are splendid, but Max Byrd’s historical novels about the third and seventh presidents bring both men alive in ways that only a literary imagination can. One measure of Lincoln’s greatness is that not even a curdled cynic like Gore Vidal could resist the spell in his novel “Lincoln.” To understand Huey Long, read T. Harry Williams’ masterful biography, but then get inside the scoundrel’s skin by reading Robert Penn Warren’s portrait of Long as Willie Stark in the novel “All the King’s Men.”

And let Mallon be your archaeologist, excavating a now distant past that reminds us that things could be very much worse. They once were.