Who does the US 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. The mission seems simple enough: extract a pharmaceutical magnate from Russian soil, a volatile man who holds the secret to a deadly bio-weapon. 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.