Mafia III

After meeting Bonnie during the mission entitled "Covered in Blood," you will be required to escape the night club. On your way out of the caverns, you will come across a knife lodged into the wall and Lincoln will automatically interact with it. Throwing knives can be used to silently take down enemies, and, like most throwable items, they can be equipped via the Weapon Menu.

For the purposes of this achievement, it may be easiest to grind out the twenty kills on the first three enemies you encounter when you re-enter the nightclub from the underground tunnels. Simply hold to aim the knife and then let go of to throw it at an enemy (and kill them instantly). You can retrieve knives from dead bodies, but once you have obtained 3-5 kills, allow the other enemies in the club to kill you. When the game loads your latest save, repeat this process as needed until you have twenty kills with throwing knifes.

NOTE: If you do not wish to grind this achievement out in the nightclub, there are plenty of other opportunities later on in the story missions, especially during the final mission, "…Worse Than Dying." It's also worth noting here that throwing knives can be purchased from the Arms Dealer for $500 a piece.