Robert Harris is probably my favourite author. Fatherland, Pompeii, Archangel and Enigma are all cracking good reads. Essentials, even. However, if one criticism could be levelled at their author, it is that they all seem to follow a vaguely similar theme. Each follow a different hero on a detective-style mystery set against the backdrop of a massively powerful, but, we gradually find out, fundamentally corrupt, political instituation, where the denouement sees the hero's actions sending shockwaves through the system in which he lives.
The novel Imperium takes a break from this theme. We follow Marcus Cicero, Roman lawyer, orator and statesman, as he follows his dream of becoming one of Rome's two Consuls.
Harris excels in creating three-dimensional characters (Dan Brown, sit up and take note, with your bland Hollywood cut-outs). Imperium is populated by alternatively brilliant, flawed, amusing, venal and/or monstrously cruel Romans. I followed their individual rises and falls with glee. Harris plays particularly well to Cicero's historical strength - that of his public oratory. The scenes set in the senate and court houses are worth the entry fee alone.
Having discarded the crutches of the plot devices used in his prevously mentioned books, Harris does not quite manage to recapture their cannot-put-downability. However, this means Imperium is merely very good, rather than a must-read.
On a side note, it's interesting to compare the two different, but very nearly contemporary, Romes of Conn Iggulden's Emperor series (lots of wars and disciplined Roman legions) and Robert Harris' Imperium (politicking, scheming and intrigue).