Gre za resnično zgodbo o Erin Brockovich, dvakratni ločenki in mami treh majhnih otrok, ki ne prenese krivice, zato se spravi na podleže in doseže pomembno zmago. Ko se zgodba začne, je Erin brez denarja in brez službe. Obupana prosi odvetnika Eda Masryja, naj jo zaposli v svoji firmi. Tako Erin naleti na primer zarote, s katero so prikrili dejstvo, da so v nekem mestu zaradi onesnažene vode prebivalci hudo zboleli, nekateri celo umrli. Čeprav ljudje sprva nočejo sodelovati, jih vztrajna Erin le pripravi do tega, da ji prisluhnejo. V njihovem imenu proti korporaciji, ki je kriva za onesnaževanje, sproži tožbo in doseže rekordno odškodnino.
Erin Brockovich-Ellis is an unemployed single mother, desperate to find a job, but is having no luck. This losing streak even extends to a failed lawsuit against a doctor in a car accident she was in. With no alternative, she successfully browbeats her lawyer to give her a job in compensation for the loss. While no one takes her seriously, with her trashy clothes and earthy manners, that soon changes when she begins to investigate a suspicious real estate case involving the Pacific Gas & Electric Company. What she discovers is that the company is trying quietly to buy land that was contaminated by hexavalent chromium, a deadly toxic waste that the company is improperly and illegally dumping and, in turn, poisoning the residents in the area. As she digs deeper, Erin finds herself leading point in a series of events that would involve her law firm in one of the biggest class action lawsuits in American history against a multi-billion dollar corporation.