To get this achievement you must complete the game with Jill without saving Chris and Barry.
This is fairly straight forward. After heading down into the tunnels beneath the mansion you confront Barry about abandoning you, after disarming him Lisa appears and he asks you to trust him and give him back his gun. Choose NO and Barry will be killed.
To not save Chris is easier as it requires no action. When in the lab, simply do not free Chris using the MO disks or the key. Ignore that section all together. Just unlock the two doors(B2 and B3) go up to B2 and get the Power Key, head back down and head to the area where you get the fuel canister and then fill it in the B3 room. Put Canister back and start the power for the elevator. Deal with the "FINALE" grab the Lab key once the final boss is dead and leave.
Since no one was saved, the Boss will not reappear on the roof for a 2nd battle.