Sarah Millwood
Sarah Millwood is the scheming young lady at the heart of the plot. She has been taken advantage of by men all her life, leading her to situation when the narrative commences: a lady of the evening. She sets out upon a mission to discover a young man who has not yet had the opportunity to hurt and take advantage of women and thereupon take him for everything she can get.
George Barnwell
George Barnwell is the unfortunate who enters into Sarah’s danger zone. She sets her eyes upon his innocence and goodwill only to discover he has assets far more lusty than good looks and innocence. The flattery of Sarah is about to introduce George to ugly reality.
Thorowgood
Thorowgood is the merchant of London of the title. He is quote wealthy, but of much greater significance is the name of his young not-so-wealthy apprentice: George Barnwell. Sarah’s attentions and good looks soon convince George to bend to her will and attain her goal. Which is, namely, redistributing some of Thorowgood’s wealth.
Lucy and Blunt
Lucy and Blunt are two servants to Sarah Millwood who become aware of the plot of George and Sarah to steal from their employer fairly early on. They will prove to be a fatal impediment stuck firmly into the plan.