Mass Effect 2 takes place two years after the events of Mass Effect. Human colonies are being attacked, their colonists disappearing without a trace. The game's protagonist, Commander Shepard, is forced into an uneasy alliance with the pro-Human paramilitary organization, Cerberus, in an effort to discover the cause. Evidence emerges pointing to the 'Collectors', an advanced, enigmatic race of insect-like humanoids. Adding to the threat is the revelation that the Collectors are working for the Reapers. Shepard sets out on a "suicide mission" to stop the Collectors, accompanied by a hand-picked team of soldiers, assassins, mercenaries, and specialists.