On a sleepy summer evening in Boulder, Colorado, in 1974, three young Chicano activists sat in a car at Chautauqua Park at the base of the iconic Flatirons—the giant red sandstone rock formations that sit above the foothills. Then, at approximately 9:50 p.m., the car exploded. Two days later, another car in downtown Boulder exploded, killing three more young activists. Their deaths came against the backdrop of the Chicano movement and the social justice activism of the 1960s and '70s. On this episode of Lost Highways, we'll look back at Los Seis de Boulder—the nearly-forgotten group of six activists in the Chicano movement who were fighting for student aid and representation on the CU Campus, and the unresolved mystery of their deaths.