After the first alien invasion, the nations of the Earth had to assume that the threat of another invasion was very real. As a measure of protection, the world government's dropped their differences and created an alliance that developed defensive measures unlike anything anyone had ever seen. As these new systems were getting ready to come online, the next wave of alien invaders arrived. As it was several years ago, the planet finds itself having to band together to fend off another alien attempt at conquering the human race. New heroes will emerge, but the result has to be the same.