With the Locust Horde apparently destroyed, Jacinto's survivors have begun to rebuild human society on their island stronghold. Raiding pirate gangs take a toll - but it's nothing that Marcus Fenix and the Gears can't handle. Then the terrifying life-forms they thought they'd left behind - the Lambent, creatures even the Locust feared - begin to advance across the planet.

Gears and gangs must fight side by side to stop their deadliest enemy yet, falling back on the savage tactics of another bloody siege: Anvil Gate.