Superficially, THE TRINITY invites most ready comparison to THE DA VINCI CODE. They both have practically the same elevator pitch:
"A deep rot in the Catholic Church leads to murder in order to cover up an ancient secret that would shake the religion to its core if revealed - and only our intrepid hero can solve it!"
On the plus side, Dan Brown's prose is about as elegant as a monkey with a typewriter's compared to Ambroziak's. Ambroziak also eschewed the "puzzle of the chapter" format where Brown's heroes had to solve some Junior Jumble-level brainteaser every hour or so in order to, you know, outwit the largest, richest, oldest, most powerful organization in the world. Ambroziak's mysteries are a bit more organic to the plot.
Unfortunately, there is quite a bit of soap opera which crept into the story and began to overpower what was basically an interesting conspiracy novel.
(Warning: from here on out there may be spoilers.)
I'm hardly a rosy-cheeked true believer, but I do know that Catholic clergy try pretty hard to keep to their vows of celibacy, or at least keep it under their birettas if they don't. In THE TRINITY most of the characters were clerics, and every single one of them was banging as many other people as possible, and then admitting it to anyone who asked. And everyone seemed to be somebody else's father. In fact, by the third or fourth time literally every character of the younger generation had accused literally every character of the older generation of being their father, I began to wonder what the point of all this was. A single paternity sub-plot could have been mildly interesting. I counted no less than four in this novella-length work. Then it turns out there are secret twins, some of whom are gay lovers, and people planning their lives around cryptic messages, sometimes from anonymous parties, and on and on. By the end I felt like I had read an entire season of a soap opera.
So I can't recommend THE TRINITY unreservedly as I have with every other work of Ambroziak's I've read. It gave me some serious suspension of disbelief issues. Still, it is Ambroziak, and she writes with great finesse. A particularly compelling and tragic death scene toward the end of the book nearly redeemed the whole thing for me, but not quite. Perhaps if you have a higher tolerance for melodrama than I do - or perhaps, if, after reading this review, you at least go in knowing that this is the religious conspiracy version of "Trapped in the Closet" - you'll enjoy it more than I did.