The Doomsday Key reminded me a bit of The DaVinci Code, except with a covert government agency involved in the search. The Sigma Force, commanded by Gray Pierce, is called in to solve a mystery that began in the 12th century after 3 murder victims are found marked with a symbol that resembles a pagan cross. The murder victims were seemingly unrelated except for the symbol, until more details come to light about Viatus, a Norwegian petrochemical company that is doing biogenetic research with genetically modified foods. Viatus' owner is a member of The Club of Rome, a group who is concerned about population growth and is working to limit growth, sometimes in outlandish ways.
Gray is aided by his very capable colleagues in a race to find the answer to the mystery of the cross, an answer that will save his ex-lover's life. (I can't explain that part here, you just have to read it.) With lots of non-stop action and unexpected twists and turns, it was a fun book to read. The beginning was a little slow, the plot kept jumping around from setting to setting which was confusing at times, but once I got into it, I really enjoyed. There were a few f-words unfortunately. Most of it was relatively clean, and then that word would be thrown in, much of it came from the Senator and didn't show up until halfway through the book. (page 226, I believe) Rated R for language.