S.T.A.L.K.E.R.: Shadow of Chernobyl
as soon as you enter, kill all the bandits and head downstairs. in the big room a bloodsucker will appear. kill it. after that, some military will be coming out of a nearby hallway. go into that hallway, and kill them. dont go to the end just yet. there should be an inner hallway in that arc-hallway. go all the way to the left (by the PDA maps left) and you should find boxes under a sewer hole. there are ladders in the sewer hole. climb up it, and find the map board. behind that is Strelok's flash drive, aka "the stash". theres an AK74SU and an AK74 rapid in the nearby cupboard, as well as some supply boxes. after that, go all the way to the end (the end that leads to the military base) and you will find a controller behind you. kill it and climb the ladder. you will have finished the mission for "Strelok's stash".