The Fatimids were a Shi'ite dynasty who claimed descent from Muhammad's daughter Fatima - thence the name - and got started as a messianic movement in the early tenth century in what's now Tunisia. Their attempt to reunify the Islamic world under their form of Shi'ism failed, but they ended up ruling an empire centred on Egypt until the last caliph was disposed by Saladin during the middle of the twelfth century, and offshoots of their creed lives on to the present day, including the Druze and the Nizaris.

The books is rather heavy going, with a relentless march of names, byzantine politics, and the intricacies of Ismai'ili theology making for a dense text asking for a lot from the reader. While I come away with a much improved understanding of the general career of the dynasty, much of the detail will be forgotten soon enough, if not already.