Ostensibly a biography of the great Carthaginian general Hannibal Barca, the fact is that it's hard to write authoritatively about what the man himself was like. Most of the records were written by his enemies, the Romans, who characterized him as cruel, mad, and treacherous. However, by looking at his actual actions, a different picture emerges, of someone who was a pretty decent man for his time, considering he spent the latter half of his life at war with an enemy that wanted to destroy his nation (and ultimately did). So most of the book talks about the history of the 2nd Punic war, which was the great contest between Rome and Carthage for domination of the Western Mediterranean.
Hannibal was a strategic genius who led his army in an extended campaign against the Roman Republic, before its ultimate ascendancy. For nearly twenty years he trounced the Romans in Italy, before finally being defeated on his home ground. His archrival, Scipio Africanus, was another man of great power and genius, and he defeated Hannibal after studying him for years.
One thing that emerges from this book is how much individual personalities mattered, both in war and in politics. Different generals than Hannibal and Scipio Africanus would almost certainly have meant different outcomes. Likewise, even after losing the war, Hannibal was powerful and influential in Carthage and instrumental in getting the city to repay its reparations to Rome. Likewise, forceful personalities in Rome (like Cato, who absolutely hated Carthage) were responsible for history taking the course it did. This book is a pretty strong argument for the theory that great men shape history. (I should probably say "great persons" or "great personalities," but frankly, women didn't have much to say in either Carthage or Rome.)
There are some modern parallels if you consider the reasons why Rome and Carthage went to war, and look at the political maneuvers of the Romans, the way Hannibal had to drag the super-wealthy Carthaginians into line to get the city's debts paid, and then how he was ultimately betrayed, first by his own people and then repeatedly by other rulers whom he assisted in resisting Rome.
There is a certain tragic inevitability in Carthage's ultimate fall, and Hannibal and Scipio Africanus both came to more ignominious ends than these great men deserved.
If you like histories of Roman antiquity with a fair amount of military information (but not too much about the nitty-gritty details about tactics and maneuvers), this is a good book. It's a bit dry at times; Lamb sticks to the source material and anything that might make it more interesting -- conjectures, ahistorical personalizing of the individuals, guesses about what might
have happened -- he labels as such and doesn't go too far down that path. Hannibal himself remains more an icon than a man; if you want to hear his voice and see his personality, you'll have to resort to historical fiction.