When the CIA's most skilled operative-whose true identity is known to none-accidentally uncovers dark agency secrets, a psychopathic former colleague puts a bounty on his head, setting off a global manhunt by international assassins.

Six, a highly-skilled assassin in the deep-cover Sierra program of the CIA, is the agency's best merchant of death. However, a mission goes bad and now Six is on the run from the CIA with sociopathic former agent Lloyd Hansen hot on his trail. Aided by agent Dani Miranda and handler Donald Fitzroy, Six must be his most ruthless to avoid Hansen, who will stop at nothing to bring Six down.