Bloody Walls

The world was plunged into chaos following an accident at a bio-weapon research facility. 100% of the earth's population has been infected. There is an antidote that blocks infection from the airborne strain of the virus, but the effect is temporary. This antidote has become the de facto currency of the new world. You have been informed that an enormous quantity of the antidote is being stored on the last floor of a bio-weapon lab.