Ceja had stumbled into the noxious muck of systemic discrimination in the rapidly growing temp industry. Around the country, temp agencies have used code words, symbols and gestures to illegally hire workers by sex, race and age. Whether filling orders for only white workers or only Latino ones, the tactics often hit black workers the hardest. As Ceja underwent a crash course in this hidden system, an advocacy group called the Chicago Workers’ Collaborative was devising a counteroffensive.