The year is 1973. Life is normal on the Island of Sodor. Contracts were being made, and buildings being built. A nuclear power-plant on the Brendam had been built, but after that... all hell broke loose.

The house is being a nice house for Scooby Doo and the other mystery solvers are having a great party until the four monsters kidnapped the mystery solvers and now Scooby Doo and the other sidekicks are the only hope to save them and solve the mystery before it's too late.

Years of poor maintenance and filthy work conditions, the Sodor ironworks begins to leak a poisonous liquid. The rest is chaos.