(These are 2 separate books, but they join seamlessly at the middle, so I'm treating them as one story.)
Graves' classic historical novels (written in the 1930s, about Ancient Rome circa AD 1) follow Tiberius Claudius, adopted grandson to the Emperor Augustus (if I remember right), through several generations of poisonings, exiles, executions, and frame-ups, as his relatives compete for the Emperor-ship. Claudius--deemed an idiot by his family, given his various physical infirmities and a serious stammer--manages to outlive his power-hungry, poison-happy (but brilliant, in her own bad way) grandmother, Livia; her corrupt son, Emperor Tiberius; and the downright mad Emperor Caligula, to eventually become Emperor himself. (This is all on the back of the book, I swear. I'm not ruining any more than the blurbist did.)
Both books are excellent--full of detail, but not so laden down with historical facts and asides that they're difficult to read (though I learned plenty about battle tactics, that's for sure). They're narrated by Claudius himself, in the form of his "memoir", I suppose, and are the sort of books that leave you dazzled by the sheer magnitude of the project. How many years of research went into writing this? I want to know.