He was just a normal guy. Sure, there was that incident with the escaped gorilla, but otherwise he was just a simple plumber, living in Brooklyn.
But then one day he and his brother Luigi were on a job, in the basement of an ancient library. Mysterious creatures, like twisted turtles and crabs began to crawl out of the pipes and they were hostile. Armed with wrenches and mallets, the two brothers fought their way through the basement, but then Luigi fell into a bottomless well. Mario had no choice, but to follow.
After becoming unconscious Mario found himself to be trapped in a strange land where time and space lost all meaning, and horrible creatures ruled by the ancient Dinosaur King Bowser, wandered the wastelands.