This is the mystery novel that started it all: The gruesome legend about the "demon barber of Fleet Street." Many people still believe that Sweeney Todd and his aide, the pie-baking Mrs Lovett next door, were real people living at the turn of the century 1800, the time period in which the story is set, but The String of Pearls is in fact pure fantasy, based on a French myth which has been traced down to the 17th century, "The bloody legend about the barber and the patissier." The earliest known version of this myth can be found in a book from 1612, written by the priest Jaques du Breul. However, The String of Pearls is a very thrilling and suspenseful story in its own right.

The novel was published anonymously as a serial in the penny magazine The People's Periodical and Family Library, in 1846-47. It was written by either James Malcolm Rymer (1814-84) or Thomas Peckett Prest (probably 1810-59), but presumably by both in collaboration. Rymer and Prest were the kings of "penny dreadful," also responsible for Varney the Vampyre (1845-47), the most successful penny dreadful ever and a precursor to Bram Stoker's Dracula.