Five years have passed since the incident at Denver, Colorado. Back then, most people didn't think of biological warfare. Those that did normally only did so as just ideas in the corners of their minds. Only a few ever thought of a true disaster that could happen from biological weaponry, even though it had been outlawed across the world. Five years can change a lot, it's certainly changed everyone's viewpoint on wether a biological disaster can occur or not.

It started in a research lab in Denver. During a routine emergency procedures test, emergency generator #3 exploded from a fault. The explosion resulted in a chain reaction with the generators around it, eventually blowing out part the reinforced walls of the lab. The media quickly jumped on this, but only reported that it was a tragic accident caused by a fluke. After the death toll and injury toll had been reported, people went on with their everyday lives. They didn't think much of it, just an accident. Those kinds of things happen all the time... All across the world.

Three days later, a man in tattered and slightly burned clothes began approaching a truckstop. The owner saw him and quickly opened the door to invite him in. The man looked like he hadn't eaten for days, and had a limp that suggested his ankle was injured severely. The owner felt good for being able to offer the man food, water, and a call to emergency services to get his injuries checked out. The man let out a skin-crawling moan when he was four feet away and lunged at the owner, catching his foot from lunging so early. The store owner manage to shake the man off, but only after a bite had been taken out of the side of his leg. The owner shut and locked the door, trying to find the phone to call the police. By the time he had found it and reported the man, the man had disappeared completely from sight. The store owner went home that night, feeling a little sick from the confusion of why the man had bitten him.

The next day, the truck stop owner's wife woke up startled by the screams of her ten year old daughter. She ran into her room to find her husband pulling her intestines out with his mouth. She hit him as hard as she could, trying to knock him away. He stumbled and fell. She grabbed the body of her daughter and ran to a phone to call the police. She heard her husband stumbling down the stairs and cried as she realized she had nowhere to run to. She grabbed a knife and drove it into his chest as soon as she got the chance to, but to no avail. She stumbled backwards and tripped over her daughter's foot. Her husband approached her and bent down over her, uttering the same moan he had heard from the man that had bitten him. He bit her neck and ripped her carotid artery out, spraying the counters and walls with blood. The police broke the door down and ran into the house, pausing for a moment at the horrendous and grotesque sight before them. They opened fire on the man's torso, but it did no good. He reached one of them and managed to bite the officer before a bullet zipped through his head.

The attacks spread from there as more and more people, and even animals, began having an insatiable lust for flesh. The media began reporting it as cult members practicing their beliefs and recruiting more people every day. Soon the infect reached overseas as people before they turn boarded onto boats, planes, etc. By the time the population realized what was really happening to them, it was too late to be simply stopped. They began banding together in multitudes in stongholds to defend themselves. Those that didn't have good defenses and supplies soon became their tomb as the zombies began to overrun them.

Two years after, the zombies started showing signs of evolution and learning. They were moving faster, and learned ways against defenses. More strongholds began falling before the people had time to realize what the zombies were doing. What used to look like a haven to survivors that had been moving from place to place started to look like their worst fears when they came upon them. The remaining strongholds learned of what the zombies were doing and began switching their defenses out at regular intervals to try and keep the zombies from learning any way around them and into the stronghold.

Five years have passed since the initial incident. Countless new creatures have been spawned from the instable evolution that are affecting the infected, rooting from man, animal, and even a few plants. A group of seven gather together in a stronghold five miles out of Lawton, Oklahoma. They all realize that the defenses aren't being changed regularly enough and that too many people were gathered in the stronghold. It was time to do try and do something before it was too late. They agreed to pack up and set out for Denver, Colorado. They wanted to find the old research center where it all started, and maybe find a way to cure whatever was happening. Or they would die trying.