Griffith Gaunt is a tale of a poor man who makes his fortune and a fine living, but has one weakness in the form of an insane jealousy. This weakness prevents him from being happy in marriage with Catharine Peyton, a Cumberland heiress, so he leaves her, finding a new romance with a lovely innkeeper Mercy. Griffith assumes the identity of his illegitimate brother, Thomas Leicester, and marries Mercy, but his passion again leads to jealousy which drives him to trials and tribulations that surpass false representation.