The Killdozer story revolves around Marvin Heemeyer, a welder and small business owner in Granby, Colorado, who in 2004 became enraged over disputes with city officials and local businesses that he felt had wronged him, including zoning decisions and fines. In response, Heemeyer secretly modified a Komatsu bulldozer into an armored vehicle by welding thick steel and concrete plating over it and installing cameras and guns inside, creating what became known as the Killdozer.