Commander Gray Perce and the Sigma Force confront humankind's greatest threat 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. The ultimate nightmare is locked within a talisman buried by a dead saint--an ancient artifact known as the Doomsday Key--and a secret that has already claimed the lives of a famed geneticist, a Vatican archaeologist, and a...

"Former Army Ranger Tucker Wayne and his war dog Kane are thrust into a global conspiracy that threatens to shake the foundations of American democracy in this second exciting Sigma Force spinoff adventure from New York Times bestselling authors James Rollins and Grant Blackwood. Tucker Wayne's past and his present collide when a former army colleague comes to him for help. She's on the run from brutal assassins hunting her and her son. To keep them...