Bessie, an aspiring actress, and Jo, who wants to be an archeologist, are employees of the fictional American Radium Factory whose dreams are derailed when Jo falls ill.
The cause, they eventually figure out, is radium, a finding American Radium vehemently denies despite having research to the contrary.
The Cavallo sisters, along with other dial painters who have fallen ill, take the company to court on behalf of Jo and the other women who have become sickened by ingesting radium.