I found it. It's amazing how much you realize you read when you start looking for a particular book. I was pulling paperbacks out of every nook and cranny till I found it, but I see you have the link provided to you.
Anyway, my kids bought it for me for my birthday by mistake. They really intended to buy me Angels and Demons, but didn't remember the title. I started reading it, and it seems to be written fairly clearly, investigating the lineage of Jesus Christ among other subjects like the Knights Templar.
Written by Michael Baigent, Richard Leigh and Henry Lincoln.
Ben-Hur by Lew Wallace was considered scandalous in its day, and now the Church endorses it. Go figure.