KEMO city was once a rich and majestic place that was the hub for hovercar production. Over time its economy steadily declined and the city became a sweeping slum inhabited by the dregs of humanity. A wealthy company named OmniCorp promised to clean up the city and erected a large wall around it, effectively shutting everyone inside like a giant prison.

In an experiment to control the restless and violent citizens of KEMO city, OmniCorp introduced a chemical called Hydergine 344 into the water supply. The experiment was a failure and caused insanity in over half of the population. Those affected became violently homicidal.

Drake Edgewater is a simple taxi driver. All he wants to do is escape the city before it becomes too late. Posessing only his own checkered cab, Drake runs fares and packages around the city so that he can save up enough to pay for the necessary papers to be let out of the only exit in KEMO city. On the way to his goal he must continually outfit his cab with bigger and badder weapons to keep himself alive amidst the madness that surrounds him.