The narrator of the story introduces Joseph Andrews, who is the brother of a famously virtuous woman named Pamela. Joseph is a capable, handsome boy who ends up tending animals for Sir Thomas Booby. There, he attracts the attention of Lady Booby, who makes Joseph her footman. When he’s a little older, he travels with Lady Booby to London, where, after Thomas Booby’s death, she tries to seduce Joseph. Joseph, however, remains committed to chastity, just like his famous sister. This annoys Lady Booby, and when her scheming maid Lady Slipslop tells lies about Joseph being a scoundrel, she uses it as an excuse to fire Joseph.
Joseph heads back from London to the country, hoping to see his longtime love Fanny. She used to be a chambermaid for the Booby family, but Joseph hasn’t seen her for a year. On his way back, however, Joseph is mugged and robbed of everything, even his clothes. He suffers serious injuries and ends up at the inn of Mr. Tow-wouse, where everyone believes that Joseph will soon die. Only the kind chambermaid Betty gives Joseph any aid. Joseph does eventually recover, however, and at the inn he happens to run into his old friend Abraham Adams, a bookish parson who always carries around a copy of the works of Aeschylus.
Abraham Adams hopes to sell some books of his sermons in London, but as he checks his bag, he realizes that his wife, Mrs. Adams, replaced several of his books in his bag with shirts. He decides to go back to fetch his sermons, which means that he and Joseph will be traveling in the same direction. They travel together, sometimes by coach, and in one coach they hear the long story of a young woman named Leonora whose lover rejected her.
At one point, Adams gets distracted and goes off on a long walk on his own. He happens to hear the shouting of a woman being attacked, so he rushes to fend off her attacker. It turns out this woman is Fanny—the very woman that Joseph was looking for. Adams takes Fanny back to a local inn, where Joseph and Fanny are joyfully reunited. The next day, Adams struggles to pay their bill at the inn, but he finally manages to get a loan from a poor pedlar.
After leaving the inn, Adams, Joseph, and Fanny are in a field one night when they hear voices that they believe are murderous ghosts (which actually turn out to be people trying to steal sheep). The three run off and find themselves staying with Wilson. Wilson is a gentleman who tells a long story about how he used to be a rake who wrote plays, womanized around London, and got thrown in jail for debts. Eventually, however, he married a woman named Harriet and has been happy ever since, except for the fact that he has a son with a strawberry mark on his chest who was stolen from him at a young age.
After more traveling, Joseph, Adams, and Fanny finally make it back to their home parish. Lady Booby has also returned from London, having passed them along the way. Joseph is eager to finally marry Fanny, but Lady Booby still pines for Joseph, and so she concocts a plan to prevent them from marrying. She goes to Justice Frolick and arranges for Joseph and Fanny to be sent to prison over stealing a twig, but her nephew, Squire Booby, knows the justice and prevents this. This is because his new wife, Pamela, is Joseph’s sister, so Joseph is part of his family. Lady Booby tries a new approach, asking Squire Booby and Pamela to convince Joseph that Fanny isn’t of a high enough social class for him, but Joseph isn’t convinced. Around the same time, the evil Beau Didapper tries to rape Fanny, increasing Joseph’s eagerness to get married as soon as possible so he can protect Fanny.
The poor pedlar from Joseph, Fanny, and Adams’s journey home makes a surprising reappearance when he saves Adams’s son Dick from drowning. He has even more shocking news to share with everyone: he knows that Fanny’s real parents are Gaffar and Gammar Andrews, meaning that she is Joseph’s sister, and the wedding must be called off.
The pedlar’s story causes confusion and temporarily stops the wedding. But as Gammar Andrews reveals after she arrives, Joseph is not actually her biological son. As it turns out, Joseph is actually Wilson’s stolen son; he was swapped in the cradle with Fanny by a fortune-teller visiting Gammar. Wilson himself arrives to confirm this, and Joseph reveals that he has a strawberry mark on his chest, just like Wilson’s lost child. The wedding is back on, with Adams conducting the ceremony. Joseph and Fanny live together happily with Joseph’s parents, and Fanny is soon pregnant. Meanwhile, Lady Booby goes back to London and takes up with a young captain who makes her forget all about Joseph.
