Monsanto tells the true story of young, untried attorney Brent Wisner (Powell) who takes on a seemingly insurmountable case against the giant U.S. chemical company Monsanto on behalf of Dewayne “Lee” Johnson (Mackie) who used Monsanto’s best-known product Roundup, a wildly financially successful weed and grass pesticide killer, as part of his job as a high school groundskeeper. During the trial, Dr Melinda Rogers (Dern), the chief toxicologist of the Monsanto Company, testifies with certainty that Roundup is safe.