Contract J.A.C.K. is a sequel (spin-off) to the The Operative: No One Lives Forever and a prequel to the No One Lives Forever 2: A Spy in H.A.R.M.'s Way, even if the game is released after NOLF 2. J.A.C.K. stands for: Just Another Contract Killer.
In the game the player takes the role of John Jack, a an assassin who is recruited by Dmitrij Volkov to work for H.A.R.M., againt another criminal group called Danger Danger, wich is lead by Il Pazzo.