On a hostile volcanic badlands colony, geothermal processing stacks — ceramic and alloy filtration towers — dot the ash plain. They were designed to filter sulfuric particulates, but when a hygiene protocol error lets unchecked containers reach the surface, an aggressive species of fist-sized alien ants attacks the colony.

The stack-towers are warm, sealed, and perfect places to breed. Our story begins when the ants have already invaded half the colony, and the situation is no longer classified as a biological hazard, but as a biological infestation consuming critical infrastructure.

A sapper team enters Stack 7 to recover a tactical datastore and stop the ants before they reach the next filtration stacks.

But the ants do not only kill people — they convert machines, weapons, wounded soldiers, and living bodies into hive materia ...