On April 20, 2010, a deadly explosion on BP’s Deepwater Horizon offshore drilling unit resulted in the largest environmental disaster in American history. To clean up the estimated 130 million gallons of oil that spilled into the Gulf of Mexico over 87 days, chemical dispersants were used in unprecedented quantities, and the public was assured that they were safe. Almost immediately, local residents and workers began to develop health problems. Nearly a decade later, they are still suffering the consequences, with no one held accountable.

Mark Manning, a former deep-sea oil-field diver turned filmmaker, began his investigation into the Deepwater Horizon disaster soon after the spill began. In the intervening years, he has uncovered disturbing evidence of coordinated efforts between the petrochemical industry and the federal government to cover up an ongoing public health disaster. As the federal government now plans the world’s most extensive offshore drilling expansion, with a blanket approval of a chemical dispersant clean-up plan, The Cost of Silence is an urgent exposé of the outsize power of Big Oil and the dangers of offshore drilling.