Something lurks in the dark corners of space, something powerful enough to kill a Reaper. Investigation leads Commander Shepard to the world Despoina, to seek aid of the mysterious creature that resembles a Reaper, it's creator. But they remain a mystery no longer to the Reapers either. The unity of their creators and Shepard is being perceived as a threat. And a reaper itself arrives to the ocean world. Shepard dives deep under the planet's ocean and meets this being, a Leviathan, leaving behind his squad on the surface of water, on a shipwreck. Leviathan refuses to aid Shepard, since no other cycle was able to defeat the Reapers.
But Shepard makes the Leviathan realize that Reapers now know of their existence and that this cycle is different, that Sovereign and Collectors have fallen. "You are an anomaly, yet that is not enough. Your confidence is singular. But what of those that follow you? If they can survive the Reaper forces, then we will know that your victories are not just a product of chance. Only then we shall give into this war. But not for you or any lesser race. We were the first, the apex race. We will survive. In shadows if your squad falls, in battle if they do not." The Reaper sends it's forces from the skies. As the rain they fall straight down upon the shipwreck and attack Shepard's squad, who are still waiting on Shepard. To prove themselves worthy in the eyes of the apex race, that they are useful tools against the reapers, Cortez, Liara, EDI and Javik must deal with the reaper's ground forces.