This is the second volume of Fabbri's series on Vespasian, who ultimatly became emperor and reigned from 69 to 79 AD. It has the same ingredients that made volume 1 (Tribune of Rome) so successful, but also a few differences.
The main originality of this series is the choice of character, with Vespasian as the main hero. This volume (when compared to the previous one) also gives much greater importance to his elder brother Sabinus to the extent that I wondered, at times, whether there was one or rather two heroes in a Simon Scarrow kind of way (Cato and Macro, of course). Another parallel is that, just like in Scarrow's Praetorian, Rome's Excutioner is mostly about Rome's horific and ruthlessly competitive politics. The main difference is the time setting: the story here takes place under the reign of Tiberius (AD 14 to AD 37 and, more precisely for this book, between AD 29 to AD 31) and tells about the fall of Sejanus, Tiberius' praetorian prefect and right-hand man. Scarrow's piece was taking place during the last months of the reign of Claudius (AD 41 to AD 54). Both books describe the atmosphere of paranoïa and terror that exists in the higher circles, including all of the Senate, and the ruthless fights between various factions for supreme power, but Fabbri's focuses more on the terror, horrors and depravity of Roman high society.
Another deliberate originality of this book is that Robert Fabbri has chosen to maximize dramatic effects and has systematically picked the worst possible interpretations he could select for the characters of Tiberius, Caligula and even Claudius. To some, these choices may seem somewhat of a caricature, although they are grounded and extracted from the written sources. This is because, to a large extent, the sources on the reigns of these three emperors were written after the deaths of the respective emperors and may, as was very often the case in Rome, have a clear tendency to "blacken" the name of the deceased predecessor. So Tiberius - one of the most maligned Emperors is all of Rome's history - is painted as paranoïd, sexually depraved, undecisive and a madman that tends to have anything and anyone unexpected put to death. Caligula is also paranoïd and Robert Fabbri has had a bit of a field day with both his sexual excesses and his incest with his sisters, and the (alleged by his opponents) sexual excesses of Tiberius. Claudius, pretending to be the fool that he is not, is ruthless, over-ambitious, but not as clever as he think he is.
These interpretations, while adding a good deal of drama, may also raise a bit of a plausability issue. First, any of Rome's Princeps (and any of the following Emperors right to the end) would need to be - and overtime became - somewhat paranoïd. This was one of the job's requirements if you wanted to survive in it, although there were others, such as an intimate knowledge of all of the main players (the senatorial families) and their respective ambitions (to buy them of and play them of against each other), and the ability to be decisive. For instance, Tiberius, however unsympathetic he may have been, managed to remain Emperor for 23 years - that is longer than any other Emperor during the first 250 years of the Empire (up to, and including Septime-Severus) with the exception of Augustus himself. So, he very probably wasn't as awful as the book makes him up to be.
Another (very good in my view) interpretation has been to show the ambivalence of Antonia (the mother of Claudius and the daughter of Marc Antony and of Octavia - sister of Augustus). She is the archetype of the noble Roman, ready to sacrifice everything for the greater good of Rome. However, her other side is also shown. Antonia seems to have been just as power-hungry, ruthless and realistic as any of the others, as opposed to only motivated by stopping Sejanus. In reality, she is a realist and the sacrifice she makes is the price to pay to ensure the survival of the rest of her children and grand-children under the reign of Tiberius.
On the plus side, also: the book is fast paced, with something happening every 20-30 pages at least, although, contrary to what another reviewer seems to imply, there is only one battle in the whole book (the storming of a fortress on the Danube). However, it is griping because of the multiple plots and intrigues as one side tries to gather evidence against the other side which will use any means to prevent it from succeeding. Another plus is that this book has been thoroughly researched by the author. Regardless of whether you agree with the author's interpretations or not, and his tendency to give credit to all of the slanders levelled at the various members of the imprerial family, he certainly has done his "homework".
One glitch, however, which turned out to be annoying at time: there were quite a lot of typos in the copy I read. It didn't, however, stop me from finishing the book in 9 hours of solid reading. Note that this is one of these books that you should start on a Friday evening. Otherwise, you are definitly running the risk of serious sleep-deprivation!