Who does the U.S. government call upon when a mission requires perfect stealth, execution, and discretion? Meet the newest recruits to the expanding Sigma Force universe--former Army Ranger Tucker Wayne and his stalwart companion, Kane, a military working dog of exceptional abilities -- in:THE KILL SWITCHThe mission seems simple enough: extract a pharmaceutical magnate from Russian soil, a volatile man who holds the secret to a deadly bioweapon. But nothing is as it appears to be. A conspiracy of world-shattering scope unravels as Tucker and Kane struggle to keep one move ahead of their deadly enemies.From the frozen steppes of Russia to the sun-blasted mountains of South Africa and Namibia, a biological threat millions of years in the making strikes out at the heart of America. All that stands in the way from a global apocalypse: one man and his dog. But can even Tucker and Kane thwart an ecological menace out of the ancient past to save the world's future?