News of an Esoterror bioscience expedition sends the investigators on a jaunt to the Brazilian rain forest, where they encounter the usual horrors of nature at its most fecund and ferocious.
After a red-herring encounter with corporate forces intent on leveling the rainforest for beef production, they catch up with their quarry and find them studying fungal infections that turn ants into zombies. They discover a fungal formulation, manipulated by an Outer Dark Entity able to change organisms on the DNA, that will launch a human zombie plague. It can’t induce a global extinction event, but it can certainly spawn enough panic to thin the membrane between realities worldwide.