An alien amoeba has invaded Earth and is taking over human bodies. These “zombies” have a hive mind and strange mannerisms, but otherwise act the same as humans. They are pleasant and personable, asking people if they want a drink of water. If someone accepts, they “share their nutrients” with them, spreading the amoeba to another host through physical contact. When in a group these lifeforms mirror each others behavior, like drones. Intelligent enough to know when someone isn’t one of them.