Justinian's Flea by William Rosen is the latest attempt at a popularization of the Justinianic period--what many consider the last gasp of the Roman Empire and the inception of the Byzantine Empire. The book is centered around the great plague that began in AD 542--the first recorded outbreak of Bubonic Plague, or the Black Death--and uses the devastation caused by this pathogen as an explanation for the collapse of both the Romans and Persians, and the rise of Islam. The book is a decent effort, but ultimately it falls flat.
To Rosen's credit, his writing flows well and his prose is generally crisp and readable. His discussion of the plague bacterium and the physiological impacts of the disease were useful for the reader with little background in medicine or microbiology. The book is reasonably well referenced but idiosyncratic in that the author goes on some fairly extended tangents that have little or nothing to do with the central premise of the book--like an entire chapter on the building of Hagia Sophia, or the discussion of Intelligent Design versus Darwinian Evolution.
That said, my primary problem with the book is that the author frequently trades style for accuracy, presenting events that are very much matters of scholarly debate as if they are closed cases. For example, he presents the accusation that Pope Silverius conspired to betray Rome to the Goths as fact, when much of the primary source evidence indicates that the Empress Theodora wanted Silverius removed. The charge of conspiracy was likely trumped up as an expedient.
The author also explicitly lays the destruction of the Library at Alexandria at the feet of Christians, going so far as to declare that the counter-claims that Julius Caesar and/or Islamic invaders burned it are not only false, but libelous. The astute reader will notice that Rosen doesn't bother to footnote this claim--because it is not supportable. In fact, the Library was probably burnt several times, and the claim that it was destroyed by Christians is probably the least credible, though most well-known thanks to popularity of atheist/deist Edward Gibbon's Decline and Fall of the Roman Empire. For a better discussion of this issue, see this article from the Ohio State University's eHistory site.
Rosen has that annoying tendency so common these days, to go out of his way to condemn the Crusades and the Inquisition, even going so far as to put them on the same level as the Holocaust and the gulags. He says:
"While imperial Rome—autocratic, militaristic, arrogant Rome—is scarcely the Kingdom of Heaven, given the horrors of the blut-und-boden states that replaced it—Crusades, Inquisition, Holocaust, gulag—one might, perhaps, be forgiven some wistfulness at its passing."I would remind Mr. Rosen that almost all of the Eastern Roman Empire was replaced by states ruled by an ideology that believed in torture, slavery, and "religious cleansing" on a scale that would have appalled the average Crusader, made Torquemada look like a piker, and served as inspiration for modern butchers like Hitler and Stalin. While I don't expect Mr. Rosen to chronicle Islamic atrocities in a book on the Justinianic era, it would be nice if he at least refrained from taking out-of-context cheap-shots at later Christian history as well.
Finally, a couple dumb chronological errors crept into the text, for instance, Augustus Caesar did not found the Roman Empire in AD 74 (p. 4)--he was about 70 years dead by then. And a single Roman Empire ruled by a single emperor existed as late as AD 395--a little over 100 years before the rise of Justinian, not 200 years (p. 36). But stuff like this can be safely blamed on whoever edited the book, not the author.
Over all, Justinian's Flea is a quick read for someone interested in the period. Ultimately, though, it is just biased and inaccurate enough to be unsatisfying. If you are truly interested in the fascinating history of the late Roman world, I would recommend going straight to the source. Try History of the Wars by Procopius. It's a truly engrossing read, containing tons of information about the Justinianic plague, and there are several inexpensive editions of the work on the market today. Also worthy of note is the Ecclesiastical History of Evagrius which is cited several times by Rosen in Justinian's Flea. Evagrius records a great deal about the plague, having lost many of his immediate family to its ravages, and survived it himself.