Mass Effect 3: Leviathan is a downloadable content episode for Mass Effect 3.
Something lurks in the dark corners of space, something powerful enough to kill a Reaper. Shepard must discover the most closely guarded secret in the galaxy before the Reapers silence it forever.
Mass Effect 3: Leviathan expands upon the events of Mass Effect 3, with gripping and emotional storytelling, compelling new characters, and powerful weapons and upgrades. Unravel the dark history about the Reapers as you race across the galaxy to discover the Leviathan.