Born to a poor mother in Newgate, who is thereafter transported, Moll has an early escape from gypsies and is put to a Nurse for care. The idea comes to her while still young that she should be a lady and that this is to be achieved by making money, but by avoiding domestic service. Clinging to money is a trait that stays with Moll to the extent that she will steal for it. On the death of her guardian, Moll goes to stay with a nearby family, who are charmed by her aspirations to be a gentlewoman. Seduced by the elder brother and later courted and married by the younger, Moll shows her first confusion between money and true emotion: the older brother pays her for each favour as he builds his seduction from a compliment to a kiss to sex.
Two children and five years later, Moll is left alone upon the death of her husband. The marriage itself is of no great consequence to the plotline, but Moll's seeming reluctance followed by her acceptance of the situation appears over and again under different guises throughout the course of the novel.
Her next 'life' is a marriage to a linen-draper, who helps her to spend what money they have and leaves the country when they find themselves bankrupt. Moll mentions this missing husband from time to time, but never for more than to reassure herself that a husband not present is no husband at all, "I had a Husband, and no Husband, and I could not pretend to Marry again..." she tells herself at first, but the protestation has no real value. It is at this point that she begins to, "go by another Name" - that is, Mrs. Flanders. Under this guise, she makes the acquaintance of, and lives with, a widow. Her friend is, however, soon married and Moll is left to reflect upon her own sad state, penniless and contactless. The thought leads to the story of another lady, jilted by her suitor because she dared enquire about his character and fortune. It is Moll's guile, spreading false rumours about the suitor and more favourable tales about the lady until he agrees to answer any questions to be married. The favour leads Moll's friend to spread rumours about Moll's (nonexistent) wealth until a suitor appears, fooled by the tale, but gentlemanly enough to accept the game Moll plays, protesting she has no wealth, while letting him believe she is jesting, to the extent that, when the truth is revealed, he cannot claim that he was lied to, but must just be relieved at any money she has. Perhaps Moll's relief at his good nature, or perhaps the realisation that what money they have will last longer overseas brings her to agree to a move to Virginia, where her new husband has a plantation. This happy episode ends miserably, as the husband's mother reveals her background and name to Moll, these being the same background and name as her own mother's. After silence for a while, Moll brings herself to tell her husband that he is indeed no husband, but her brother. The episode is brought to an end, and Moll returns to England, this time settling in Bath.
In Bath, Moll makes the acquaintance of a gentleman who, "had no Wife, that is to say, she was no wife to him...". The two are friends for a while, but eventually Moll, "exchang'd the Place of Friend for that unmusical harsh-sounding title of WHORE". Moll bears him a son, but the man's conscience begins to trouble him and he returns to his sick wife. Left with little money, Moll seeks the advice of a banker, who introduces her to a friend. The contact proves useful, giving Moll information of how to get interest on the money she has left and the banker in question (the friend) becomes attracted to Moll. He too describes his wife as none; this time because she is an adulteress. Moll persuades him that he must divorce his wife, "...the Law has furnished you with Methods to prevent that also, you may Cry her down; as they call it, "and, although she does not actually accept his proposal of marriage, she does not refute the possibility; jesting with him about marriage while avoiding signing a contract.
As the banker stays in London to proceed with his divorce, Moll travels to Lancashire, on the advice of a woman in the house where she has been lodging. She has been told that the woman's brother is rich and, indeed, when she meets the brother, he courts her. The two marry to discover that the woman, who is not his sister, but a scam-running whore, has fooled them both (or been fooled by them both!) and neither one has any money to speak of. Yet Moll is fond of her husband, who leaves her with a, "short but moving Letter" and calls out in anguish over his departure, before counting the little wealth he has left her. Jemmy (the Lancashire husband) returns, claiming he heard her cries. The two live together for a short while and Moll suggests they move to Virginia to stay near her mother. Jemmy prefers to attempt his plans to live in Ireland, but promises to return if he proves unsuccessful. Moll is pregnant when Jemmy leaves again. She lies in and, close to her time, hears from the now-divorced banker.
Remorseful that she has a child to show her infidelities, Moll agrees to a fee for a nurse for the child and returns, via West-chester, to London. She marries the banker, despite a moment of guilt, has two children with him, but is left a widow after five years. She is not left destitute, but believes herself in danger of poverty and this fear leads to the beginning of her career as a thief. The first few thefts are opportunistic and it is only when Moll returns to her 'governess' (the woman who had looked after her while pregnant), now turned pawnbroker, that she is introduced to the world of organised crime. One theft in particular, from a family in panic as their house was in flames, shocks Moll, but as always, she, "began quickly to forget the Circumstances that attended the taking them".
Becoming known to various criminals, who are not so successful as she and end up in Newgate, Moll meets with the problems of being notorious and wanted and goes into the disguise of a man, calling herself Gabriel Spencer (also the name of the actor killed in a brawl by Ben Jonson). The use of disguise enables her to escape capture when her partner is crime is caught, but even so she goes back to the lodgings she shared with her Lancashire husband (Jemmy) and tells the landlord she is waiting for her husband; actually she is waiting for the news that her partner has been hanged. A brief interlude, in which Moll reminisces about a similar case in which a lady caught for thieving blames the infamous Mrs Flanders, leads to Moll returning to London and, at Bartholemew Fair, meeting a gentleman, "extreamly well Dress'd, and very Rich..." and going with him in his coach. Drinking leads to him becoming lecherous and Moll admits that she, "by little and little yielded to everything, so that in a Word, he did what he pleas'd with me". His reward is to be robbed as he drunkenly sleeps. Upon questioning Moll, her Governess recognises the gentleman and, through blackmail, manages to sell him back his stolen property. Still, he is keen to meet with Moll again and she eventually, without being given much choice by the Governess, agrees. Moll sleeps with him and is rewarded with money. This becomes a regular arrangement, which allows Moll time away from thieving. When they break off, her life as a thief is resumed.
Moll tells us of various escapades, including her wrongful arrest for a burglary while she is dressed as a widow. This capture proves profitable, as the true thief is captured and Moll can demand reparation for the humiliation to her good name. Other guises, as a beggar, for example, are less successful, leading to her meeting with a group who want her to commit murder; a crime she will not seriously consider. Moll also refuses house burglary, but will steal from shops. Moll is finally caught attempting to steal from a drapers and is sent to Newgate. Whilst there, Moll refuses to confess to the Newgate ordinary, who urges her towards repentance, not even knowing what her crimes have been. It is a minister sent to her by the Governess that gives Moll reason to confess and prays with her. From this penitence, Moll's original sentence of death is lessened to transportation. By chance, Jemmy too is in Newgate, and Moll finds herself in a position to help him. The two of them are transported and, still having the gains of their crimes, do not travel like criminals, but rather a couple starting on a new life. When in Virginia the pair arrange to be bought then buy their own freedom and return to the land of Moll's brother (once husband). He is dead by now, as is her mother, who has left instructions with Moll's son to provide for Moll should she ever return. This is the happy ending of a so-called penitent. The flaw is, of course, that it is not an ending, merely where Moll chooses to close the story.