In order to take down The Collectors, Shepard must go through the Omega-4 Relay to strike the Collectors at their base, effectively a suicide mission.
But life is about to take a sharp turn for Shepard, as they meet Cerberus and lean of agents of the Reapers who are terrorizing humanity before they even arrive.
A month after the defeat of Sovereign in Mass Effect 1, Shepard and the crew of the Normandy scour the galaxy for the last remaining Geth holdouts.