The National Laboratory has been doing work that most people are not cleared to know about — biological research of the kind that, if it leaves the building, could reshape the world in ways that would be deeply inconvenient for most of the humans in it. The facility is now under attack. You are the pilot of Multi-Purpose Helicopter callsign Zombie 26, conducting aerial interdiction against a relentless assault. The research cannot be captured. The vectors cannot escape the city. Fly accordingly.