Taking place after the main plot of Mass Effect 2, Arrival provides an additional mission in Commander Shepard's attempts to thwart the Reaper invasion. What begins as a rescue mission for a human scientist escalates into a race against time as Shepard discovers an imminent Reaper attack on a vital resource. Arrival provides a unique experience by forcing Shepard to perform the mission without squadmates, and is the final downloadable episode for Mass Effect 2.