For Fifteen Years by Louis Ulbach is the sequel to The Steel Hammer which tells the story of a poor upholsterer, Jean Mortier who is falsely accused of murder and the tragic chain of events that follow. For Fifteen Years begins in the aftermath of the conviction when the destitute wife and daughter of Jean Mortier are taken in by the family of a character witness from the trial, Gaston de Monterey. Circumstances and deceptions lead to distrust and tension among the two families for fifteen years but the daughter of Jean Mortier and the son of Gaston de Monterey have fallen in love. The two decide they must clear the air and set out to discover the truth about Jean Mortier's guilt so that they may marry with the blessing of their parents.
