Nobody knew exactly what the hell caused it. It just happened. The Island of Sodor went from a bustling little island to a deserted, contaminated hell hole. It all happened when a shipment was sent from across the globe to Brendam Docks. A highly dangerous chemical as well as a few pieces of machinery that were to be taken down to the "Maron Research Center." Nobody knew what it was for, not even The Fat Controller himself. Only the government and the scientists that were working on the project knew.
Then one-day, out of the blue, the facility exploded. Once again, nobody knew why, but apparently the chemical got out of it's contained state and spread through the air. Everything seemed normal at first, nobody saw anything out of the ordinary. But things changed. Trees started dying. The sky went gray and the sun barely shown. This barely happened during the summer seasons People started to get sick. Terribly sick. They started showing symptoms that lead many professional doctors to believe that they were infected with a Zombie-like disease. Missing people and sightings of more mutated freaks and dead bodies around the towns, roads and railways lead the government to have Sodor evacuated. But none of them realized that whilst some humans are immune… the same cannot be said for the engines…
Most of them just grew sick. But others… others were much worse. One couldn't even describe them as the slightest bit of normal… they went from engines we all know and love to sick monsters bent on killing for parts. Not realizing what they're doing. So to prevent the disease from spreading elsewhere, The government had the bridge over the Walleny Channel blown up.
Now with engines trapped on a nearly deserted island… the ones that were immune learnt that this was no longer a place of happiness, it was a place in which you had to watch your back. It was now kill or be killed, knowing who and who not to trust, trying to survive another day in a disease stricken wasteland known as The Island of Sodor…