I’ve read a few books by Dando-Collins, and liked them all. He has produced several books on the history of a single legion, and “The Ides” which is moment by moment recounting of the assassination of Caesar.
This book is similar to that, recounting the ‘turning point’ that led to the end of the Julio-Claudian line of Emperors. First the Great Fire of Rome undercut the popularity of the Emperor Nero, and then the subsequent attempts to shift the blame and crush the conspiracies that were springing up removed what was left, until finally the revolt of Galba left Nero alone and without support. Nero’s suicide meant a four-cornered civil war for control of the empire.
Collins doesn’t come down squarely on the issue of whether Nero started the fire through agents or not. Certainly there were rumors from the time that he had, which were probably false ones. A good emperor (like Titus a decade or so later) can have his reputation enhanced by his response to a disaster. The fact that the rumors started soon and were so readily believed showed that discontent with the singing Emperor was already present before the fire.
In my opinion, it was the response to the fire that really sealed the deal. After the fire Nero re-laid out the city to have larger roads and better building codes. This change was jarring enough, but the fact that much of the city center was reserved for a huge palace complex for Nero alone probably locked in the grumbling onto Nero. “Who Profts” is an old question, and here it looked like Nero had.
Nero soon attempted to fix the blame on someone else. According to Dando-Collins, the despised religious sect that took the blame was not the Christians, who had too low a profile, but the devotees of Isis. They had a cult interest in fire, and were much more alien than even the Jews, or splinter groups of Jews were. But even this backfired, as the punishments he put on them were judged to be too extreme.
Discontent among the Senate led to plots, and failed plots led to repression and executions in a downward spiral until one plot didn’t get crushed.
Dando-Collins has a little bit at the end imagining that if the fire had not happened then there might have been a revivification of the Julio-Claudian dynasty. I’m skeptical. Nero was a flake, and had no heir. There was already discontent over that, and eventually it would have boiled over. It was probably just as well that a new line was set up, the Flavians, after the year of the Four Emperors.