The store that they are hiding in can easily be located with the aid of the map. However the door to the backroom that they are hiding in will remain locked until after Katey receives her Zombrex (if the player is giving Katey the Zombrex) 7AM to 12PM (noon) on the 27th (the third day). There is a max of 8 psychopaths/survivors on the map at one time so if there are more than 4 others active the door will not unlock (which includes the 3 survivors involved in the unmarked mission High Rollers as well as Janus Razo).
Chuck finds all the four members down there and tries to get them to follow him to the Safe House, however they refuse, claiming they are safe and have supplies. Wallace will ask Chuck to bring him a Cement Saw and Plates to build a new weapon. Once Chuck brings them back to Wallace, he is rewarded with the Plate Launcher Combo Card and an already assembled Plate Launcher. The backroom serves no other purpose at this time.