Although laborer Joe Mercer loves factory girl Katinka Jenkins, she agrees to become the mistress of Lindsay, the mill owner, in order to escape dire poverty and cruel parents. Katinka sends Lindsay's money to her family, but eventually, he finds himself unable to pay his employees, and only under Joe's influence are the men prevented from striking. Reformer John Strong, who loves Katinka's sister Olivia, visits Katinka to request that she cease her disgraceful dance performances, but he soon submits to her charms and is passionately embracing her when Olivia enters the room. Katinka then learns of the situation at the mill and realizes that the compromise of her honor has ruined more lives than her own.