Dennis Drabelle is a former contributing editor of Book World.

About midway through “Dynasty,” Tom Holland observes the end of an era, at a Roman funeral in 22 A.D. The deceased is an elderly woman named Junia. The reigning emperor is Tiberius, who, without being on hand physically, is such an overweening presence that the ancestral effigies on display do not include the most celebrated member of Junia’s family: her brother Brutus, who in 44 B.C. helped assassinate Julius Caesar, founder of the dynasty to which Tiberius belongs. Junia’s death has broken one of the last links between imperial Rome and the republic that Caesar left in shambles.

“Dynasty” is a sequel to “Rubicon,” Holland’s account of Caesar’s meteoric career. Many of us have a passing acquaintance with Caesar’s successors in the Julio-Claudian line: the ruthless, power-amassing Augustus, the paranoid Tiberius, the wittily cruel Caligula, the freakish Claudius, the showboating Nero. But as told by Holland with erudition and brio, the truth about these tyrants is more dramatic and complex than we may have thought.

Holland shows us how, after succeeding his adoptive father, Julius Caesar, Augustus won over the populace in ways that have since become tyrants’ stock in trade. By conquering distant provinces and imposing Roman rule there, he stoked his subjects’ pride. By building public works, he let them share in the spoils.

A good example of the latter approach came after the death of one Vedius Pollio, a tax collector whose administration of Asia Minor had markedly increased the revenue flow to Rome while also making him filthy rich. In his will, Pollio deeded to the emperor what Holland calls a “vast property that he had built on a spur above the Forum.” Augustus accepted this windfall only to level the site and hand it over to his wife, Livia, who, “no less conscious than her husband of her responsibilities towards the Roman people, had it rebuilt in splendid fashion, complete with colonnades and fountains, and presented to the delighted public. So, in the new age presided over by Caesar Augustus, was the selfish greed of plutocrats justly treated.”

"Dynasty: The Rise and Fall of the House of Caesar" by Tom Holland (Doubleday)

Such gestures were almost enough to make the “delighted public” overlook Augustus’s faults, among them sexual promiscuity. One might assume that imperial rutting was something to be forgiven or even winked at. Not so, Holland asserts. “Augustus’s reputation as a serial adulterer, far from boosting the aura of his machismo, cast him instead in an effeminate and sinister light. No man could be reckoned truly a man who was the slave of his own desires. Playboys who chased after married women were well known to be womanish themselves. The [emperor], it was whispered, smoothed his legs by singeing off their hairs with red-hot nut shells.”

Tiberius may have laid off the red-hot nut shells, but succeeding Augustus was a daunting assignment, especially for a poor communicator like himself. As his reign went on, Tiberius grew terrified of assassins. Consider his reaction to the earthquake he endured at his home away from home, above the Bay of Naples. Any good Roman would have taken the quake as a sign from the gods, but what, exactly, were they trying to say? The interpretation given by Tiberius — never to set foot in Rome again — seems wrong-way-round (shouldn’t he avoid the region where the earthquake hit?), but he was probably right to think that on the whole the countryside would be safer for him.

Tiberius got the natural death he wanted, which was more than you can say for some of his successors. Caligula, for one. Holland is at his best in the chapter on this flamboyant figure. Once upon a time, a soothsayer had scoffed that the boy had no more chance of becoming emperor than of riding across the Bay of Baiae on horseback. Caligula accepted the challenge. Once enthroned, he had dozens of ships lashed together to form a gigantic pontoon stretching over the bay, which he then rode across. As a display of limitless power, it could hardly have been bettered.

Caligula delighted not just in breaking with tradition but also in mocking it, as when he announced his intention to appoint his horse Incitatus as consul (one of the most prestigious offices in the Roman government). “So cruel was the satire,” Holland notes, “that it seemed to the aristocracy almost a form of madness.” Conspirators assassinated Caligula after only four years in power, then hunted down and killed his wife and daughter. “So perished the line of Caligula,” Holland writes: “dead of a joke taken too far.”

Next came his uncle Claudius, who, as Holland puts it, was “so despised and discounted by his relatives that not even Caligula had got around to eliminating him.” The slobbering misfit surprised everyone by becoming a savvy ruler, a breath of relative sanity in the Julio-Claudian madhouse.

Maddest of all was Nero, who seems to have been utterly lacking in self-awareness. The spectacle of an absolute monarch entering contests as a musician and an athlete, and then trying his utmost to excel, even though he knew that no judge would dare award him anything but first place — this is egotism as farce. As he swaggered toward his own abrupt end, Holland writes, “Nero remained true to what he saw as his highest responsibility: to delight his fellow citizens.”

This is great material, and Holland does it justice with a chiseled prose style and an eye for the luminous detail. He memorably sums up a region of interest to the Romans as “the kingdom of Armenia, a land of icy mountains, thick forests and notoriously effective poisons.” He emphasizes Roman cruelty by explaining how a soldier tasked with executing a young girl coped with the sacred tradition that forbade putting a virgin to death. He “made sure to rape her first.” And Holland shows how, with Caligula, even fawning could be fatal. Once when the emperor fell sick, a sycophant named Atanius swore “an extravagant oath. Only restore Caligula to health, [Atanius] had promised the gods, and he would fight as a gladiator.” Caligula recovered and “with a perfectly straight face . . . ordered the wretched [man] into the arena, to fight there for the amusement of the crowds. Predictably enough, paired against a trained killer, Atanius didn’t last long.”

A graduate of both Cambridge and Oxford, Holland is a master of narrative history. On the strength of “Dynasty,” he deserves a laurel wreath.

The Rise and Fall of the House of Caesar

By Tom Holland

482 pp. $30