In the opening pages of the book, the narrator tells the reader to expect a story about a woman who has lived a life of sin and crime but who eventually "dies a Penitent." The narrator says that Moll is going to write her story herself and that it is "her own history," making it seem as though this is a work of nonfiction rather than fiction. He claims merely to have helped in "finishing her story" and making it something which is suitable for publication and public consumption, putting it into "language fit to be read." In other words, the details of Moll's story and her own word choices have been made somewhat more acceptable and proper; accordingly, any episodes that could not be suitably modified in this way have been excised altogether. Even the most chaste reader, now, should not be (very) offended by what he or she reads, and the narrator says that the story of Moll's life has been modified so as not to give "lewd ideas" to the reader. In other words, Moll's story has been toned down, and the reader ought not to approach it hoping to hear all the salacious details of the life of a "whore" and a "felon."

Readers will find, the narrator claims, a work from which they might draw very useful lessons, especially in regard to the way Moll's life ends rather than the way she actually lived for the vast majority of her years. It can, he says, be applied to many "virtuous and religious uses." We can expect "wicked action" to result in unhappiness and misfortune, a condemnation of "ill thing[s]," and praise of virtue and "just thing[s]." He says that we can anticipate receiving a good amount of proper instruction, should we choose to take it. He places a great deal of responsibility on the reader to read the book in the right way and not for the wrong reasons.