 In 2061, the "Lancer" arrives and discovers a primitive race of nomads, broadcasting using organs adapted to emit and receive electromagnetic radiation (hence "EM"s).A curious satellite is discovered in orbit, at least a million years old, roughly when a meteor shower destroyed the EMs' civilization.On Earth, international commerce is brought to a standstill when mysterious spaceships drop sea creatures dubbed "Swarmers" and "Skimmers" (for their behaviour