The comic was based in Manhattan and featured the main character Michael Alexander.
Alexander is the author of a book entitled Dark Dominion, in which he explored the idea that another world occupied the same spacetime as our own. This alternate world, which housed the sub-stratum of our world, demons arose from the fears of human beings. The only way to see this hidden world was to put aside one’s fears.
The main villain, Chasm, has chosen Manhattan to be his headquarters on Earth because of the vast population on whose fears he could draw from.
Michael Alexander is not afraid to face Chasm and the demons of the Dark Dominion. He perceives this alternate dimension as an energly-filled double of our own, with various demonic-type bits of architecture added to it. Monsters tended to ride the very humans they afflicted. This is seen in a crossover with another Defiant title, Charlemagne, when he tears creatures from the minds of affected dockworkers. The same issue sees Michael befriending a super-powered ‘fish out of water’ named Charles.