When Martin's raiding guild join the latest virtual reality MMO, they discover a challenge like no other. Strata Online is a hundred floor mega-dungeon, filled with an ever-shifting ecosystem of monsters. Martin's team soon find themselves in a race against the world’s strongest guilds, all competing to be the first to reach the unbeatable game's lowest depths. Stranger still, they must now contend with Sin, a twisted morality meter which can transform a players’ class into its dark counterpart. With eternal fame and prizes on the line, Martin risks playing as a rarely chosen race; a Murovan rat-man, combined with the unusual exorcist class. But unlike other games, he will need as much courage as skill to progress. Because the deeper he goes, the darker Strata gets.