Five years after the events of the War of Liberation, humans and alien refugees are working together to forge a civilization of mutual cooperation and coexistence. However, not all of Earth's inhabitants support an interspecies alliance. With all pre-invasion government institutions being non-existent, XCOM transitioned into gendarmerie operations to enforce law and peace. They form the Reclamation Agency, a peacekeeping force that deploys squads to locales. The first of these squads is Chimera Squad, deployed to City 31 in 2040. Chimera Squad is an experimental elite force of human and alien agents, tasked with the investigation, infiltration and destruction of all underground threats that seek to promote chaos and anarchy in City 31.