Langur Skuggi, a Dokkheimien astro-cosmologist on a planet in the dark matter universe, has the task of finding a solution to the imminent extinction of his species, precipitated by their near immortality. On Vesimaa, a planet in the Light Matter Cosmos, he meets an alien whose species may have the solution to the Dokkheimien's dilemma. Tumma Varjo gets caught up in the drama of the interaction between the two species. The solution that comes out of many complications is not what Langur had planned, or could have foreseen. The first contact deteriorates into an alien invasion with devastating effects on Vesimaa's population from which the species has little chance of recovering. The long term effects on Dokkheimiens is no less catastrophic.