The Diamond neighborhood was an all-black enclave in the mostly white town of Norco, Louisiana, aptly named for the New Orleans Refining Co., an industrial processing plant. Margie Eugene Richard was raised in the shadow of a giant chemical plant operated by Shell, and witnessed her neighbors fall ill amid the toxic waste the plant emitted year after year. Her own sister, Naomi, eventually succumbed to a rare lung disease linked to environmental hazards...