At Princeton University, a famed geneticist dies inside a biohazard lab. In Rome, a Vatican archaeologist is found dead in St. Peter's Basilica. In Africa, a U.S. senator's son is slain outside a Red Cross camp. The three murders on three continents bear a horrifying connection: all the victims are marked by a Druidic pagan cross burned into their flesh...

At Princeton University, a famed geneticist dies inside a biohazard lab. In Rome, a Vatican archaeologist is found dead in St. Peter's Basilica. In Africa, a U.S. senator's son is slain outside a Red Cross camp. The three murders on three continents bear a horrifying connection: all the victims are marked by a Druidic pagan cross burned into their flesh.

The bizarre murders thrust Commander Gray Pierce and Sigma Force into a race against time to solve a riddle going back centuries. Aided by two women from his past--one his ex-lover, the other his new partner--Gray must piece together the horrifying truth. But the revelations come at a high cost, and he will have to sacrifice one of the women at his side.

In an adventure that races from the Roman Coliseum to the icy peaks of Norway, from the ruins of medieval abbeys to the lost tombs of Celtic kings, Sigma Force confronts humankind's greatest threat, bidden inside an ancient artifact known as the Doomsday Key.