In 1871 Chicago an undercover detective gets a job as a porter in a somewhat disreputable saloon in order to get information on a stolen painting, which he believes will be fenced there by the thieves. He soon falls in love with the saloon owner's daughter, who believes him to be just a porter. Soon his undercover work puts him and the girl in danger, from both the criminals who stole the painting and the infamous Chicago Fire of 1871.