The future of the Earth is in serious jeopardy in this made-for-television movie spun from the Fox science-fiction series "Alien Nation," the saga of a Los Angeles detective (Gary Graham) and his alien partner (Eric Pierpoint). In Dark Horizon, the partners discover that the Purists have unleashed a virus intended to rid the planet of all Newcomers. But is it too late to put the lid back on Pandora's box?