In Season 3, Eliza finds herself investigating more fresh and surprising mysteries, ranging from a disappearing magician to police corruption, as she struggles to build her detective agency. Growing competition from a rival agency creates new problems, and all the while she is still juggling her relationship with Inspector William Wellington, the Duke.

Detective Fitzroy sees one of his colleagues plant evidence on a suspect. With Duke away, Fitzroy turns to Eliza and hires her to look into a case of police corruption.