Contrary to what another reviewer has stated, I should make it clear that nowhere in this book is there any mention whatsoever of the infamous work of fiction, "The Protocols of the Elders of Zion". This other reviewer clearly has not read "Talisman", and it would appear that they gained their erroneous opinion from a misunderstanding of another previous review. The authors of this book do mention at one point that certain Islamic extremists believe, for some reason, that the Freemasons are helping the Zionist (i.e., pro-Israel) cause in the Middle Eastern region. Other than this largely irrelevant point, there is nothing even remotely connected with the Protocols in this work.
As for the real content of the book, it gives a brief overview of history in which the authors attempt to illustrate the connections between certain esoteric sects. The Gnostics and Hermetics of the Roman period are portrayed as having received some of their inspiration and ideas from Ancient Egypt, and the later Cathars and Bogomils of medieval Europe are theorised to have both been the inheritors of this Gnostic and Hermetic knowledge. A moderate case is set forth to support this basic thesis, including a comparative look at early Hermetic writings and the Egyptian "Book of the Dead", but it seems the authors did not spend enough time on their ideas to give them real justice, I feel.
There are a few minor errors in this book that I noticed, which implies there may be more. On page 377 it is stated that on "27 December 1789 Pope Clement XII signed the order for Cagliostro's arrest." This can hardly be correct, considering Pope Clement XII died in 1740! It is also stated on page 473 that Julius Caesar founded the world's first republic; yet the Roman Republic had effectively ended before Caesar even came to power. He introduced the Julian calendar in 46 BC, too, not 48 BC as stated in the book.
This is a fairly interesting book at times, but you will probably not find everything in here convincing. Particularly feeble is the idea that certain famous cities have been aligned intentionally in certain manners of esoteric significance; for instance, so that the sun and Sirius both align with Pennsylvania Avenue on 12 August - obviously just a coincidence, in my opinion. Certain buildings or their layouts are said to have been secretly copied from ancient ones; maybe the authors have keener eyes than I, but I fail to see any correspondence whatsoever between the layout of the Louvre Palace and the Luxor temple at Thebes.
Ultimately, though, this is worth reading, but do not expect it to astonish you with its arguments and evidences set forth.