It's the year 2378, and following countless wars and acts of terrorism, Earth's nations have sealed themselves beneath huge domes. For any aliens seeking refuge, they must be processed on a holding station tethered above the planet and run by an organisation known as The Church. Any off-worlders seeking to enter Earth illegally are tracked down by Alien Hunters such as Marshall Holt, whose half-breed nature means he is psychically attuned to his quarries.
