Vanity Fair seems like it's going to be one of those blonde girl/brunette girl parallel lives stories, but the plot takes so many twists and turns that this formula ends up cast aside.
Two girls graduate from a finishing school. One, Becky Sharp, is the daughter of an alcoholic, broke art teacher. The other, Amelia Sedley, is the daughter of a very well-to-do middle class investor. Because of their very different childhoods, they have already learned different lessons about the world. Becky has learned that she needs to be totally self-reliant to get anywhere in life, while Amelia has learned that she will always be protected and so can remain a totally passive person.
Becky is destined for being a governess, but Amelia takes her home to spend a few days with the Sedleys before Becky's job starts. When Becky finds out that Amelia has an older brother who has an excellent post in India, she decides to try to charm him into marrying her. However, Jos Sedley turns out to be a whole other kettle of fish: fat, vain, super shy around girls, and in general quite a character.
After much flirting, singing, and intimate conversation, Becky still hasn't gotten her proposal. Finally, Jos, Amelia, and Becky decide to go to Vauxhall, a garden concert hall, nearby. With them also comes George Osborne, Amelia's almost-fiancé, and William Dobbin, George's close army friend, who takes one look at Amelia and falls head over heels. George is about as vain as Jos, but also handsome. He has no desire to have Becky as his sister-in-law, and he mocks Jos for being attracted to her, thus spoiling any chance Becky might have at the marriage.
Becky leaves the Sedleys and goes to the Queen's Crawley estate to be a governess. She makes the best of her situation there. In addition to teaching the Crawley children, Becky becomes the secretary and informal estate manager to Sir Pitt Crawley, the Baronet, who is a nasty, vicious, cheap, litigious old man. Becky mostly leaves her pupils alone and they love her for that. She pretends to be pious and awed by the intellectual abilities of the prissy and dainty Pitt Crawley, Sir Pitt's oldest son. She gives a flirty cold shoulder to Rawdon Crawley, Sir Pitt's youngest son, who is a very macho army guy.
Sir Pitt has a younger brother, Bute Crawley, who together with his wife is very jealous of Becky's sudden popularity. Sir Pitt also has a half-sister, Miss Matilda Crawley, who is a single, very rich, fat, gross, highly obnoxious old lady. Miss Crawley loves her nephew Rawdon, and everyone expects that when she dies, she will leave him all her money. When she comes to visit, everyone kisses up to her, but Miss Crawley becomes obsessed with Becky and takes her back to London. There, Miss Crawley falls ill, and Becky takes excellent care of her. After a few months, Sir Pitt comes to make Miss Crawley send Becky back to his estate. When Becky seems hesitant, Sir Pitt proposes to her. Becky is shocked, then shockingly reveals that she is married already.
Becky runs away from Miss Crawley's house, leaving a note that reveals that she is married to Rawdon. Miss Crawley is furious and changes her will. She decides to never see Rawdon or Becky again.
Meanwhile, Amelia's father's business starts to fail. Napoleon has escaped his exile in Elba and is massing another attack on Europe. This causes the stock market to go nuts, and Mr. Sedley loses his investments. The more the Sedleys are ruined, the more Mr. Osborne, George's father, is unhappy at the idea of his son marrying Amelia. He orders his son to break off the relationship, which George says is not honorable.
Finally, Mr. Sedley goes totally bankrupt. There is an auction held to sell off all the Sedley belongings, and the family moves to a tiny house in a poor neighborhood. Mr. Sedley is angry that Mr. Osborne has suddenly cut off contact, and orders Amelia to send back George's letters and presents and to break off the relationship. Amelia does, then becomes very ill. She's got brokenheartitis.
Mr. Osborne threatens to cut off George's allowance if he doesn't sever all ties with Amelia and tries to get him to propose to a rich and vulgar heiress. George refuses and is very happy with himself. But he also starts to neglect Amelia and doesn't even bother to figure out where she and the family have moved.
Dobbin does keep track of all of this, goes to visit, sees the super-pale Amelia, and tells George that she is dying. George freaks out, goes to find her, and marries her. He doesn't tell his father, and Mr. Osborne still thinks George will come back with his tail between his legs as soon as his money runs out.
Amelia and George, along with Jos, go to the seaside resort town Bath for their honeymoon. There they run into Becky and Rawdon, who are in Bath because that's where Miss Crawley is, and they are hoping to get her to forgive them. Dobbin stays behind in London to tell Mr. Osborne that George is married. The two couples hang out together, and George loses a ton of money to Rawdon at cards and billiards. Amelia is sad that George is clearly already bored with her just two weeks into their marriage.
Miss Crawley, meanwhile, is being taken care of in her illness by Mrs. Bute Crawley, who is a tiny powerhouse of a control freak. Miss Crawley can't stand her. Finally, Mrs. Bute Crawley goes away, and Becky has a small opening. Miss Crawley decides to communicate a little bit with Rawdon, but still won't forgive Becky. In London, Dobbin tells the Osbornes about George and Amelia's marriage, and Mr. Osborne disowns his son completely.
Suddenly, Napoleon's invasion is imminent! Everyone who is army-affiliated (George, Rawdon, and Dobbin) is ordered to Belgium. Becky, Amelia, and Jos also decide to go. George and Dobbin serve in the same regiment, under Major O'Dowd and his proud Irish wife. In Brussels, Mrs. O'Dowd takes Amelia under her wing and everything is hunky-dory until the arrival of Becky and Rawdon, who is the aide-de-camp to an important General.
Becky is the toast of Brussels and immediately makes it into the highest society. George is totally captivated by her and completely neglects his wife. On the day of a grand ball, George gives Becky a note asking her to run off with him. That very night, the army gets its marching orders. George feels bad, kind of makes up with Amelia, then goes off to the front with Dobbin. Rawdon also goes off, while Becky calculates how much money she'll be left with if he dies.
No one back in Brussels has any way of getting any news about the war. At one point there's a panic, and everyone tries to flee. Jos is terrified and wants to run away as fast as possible – as do most others. Because of the sudden rush, there's a huge demand for horses, which are in low supply. Becky has two horses and sells them to Jos at a crazy price. As soon as he buys them, news comes that the allies have defeated Napoleon at Waterloo. Dobbin is OK, Rawdon is OK, but George has been shot dead.
Becky and Rawdon go off to Paris, where she gives birth to a son. She doesn't really care about the baby and mostly ignores him. Rawdon, however, totally loves his boy and becomes kind of a changed man because of him. Miss Crawley is still angry at them. Pitt Crawley marries the lovely, gentle, happy Lady Jane, and Miss Crawley is enchanted with her. Pitt and Lady Jane have a son and a daughter, and when Miss Crawley dies, she leaves all her money to Pitt. Then Sir Pitt dies, and Pitt Crawley inherits the mansion and estate at Queen's Crawley as well. Rawdon is furious, but Becky is a lot more clever than her husband. She acts like a very gracious loser, impressing both Pitt and Lady Jane with her good wishes for their prosperity.
Amelia goes totally bonkers over George's death. It doesn't help that she is pregnant and now has no means of supporting herself financially. Jos and Mrs. O'Dowd take care of her, then she goes to live in the tiny house of her parents. When her son is born, she recovers and transfers all the love she's ever felt for anyone onto him. That's kind of a tough gig for a little kid. Amelia scrimps and saves to make sure he is dressed in the latest clothes. Dobbin becomes his godfather. Mr. Osborne is still angry about the marriage and refuses to acknowledge the existence of either Amelia or her son.
Becky and Rawdon come back to England and make nice with the new Sir Pitt and Lady Jane. Becky is her usual superficially charming self. Sir Pitt likes her a lot and puts her in charge of fixing up the Crawley mansion in London. But she is unmasked faster than usual because her young son makes some innocently revealing comments (like, "I've never eaten with my mommy before!" and "Mommy never kisses me at home") that horrify Lady Jane. Still, for now, Becky is in Sir Pitt's very good graces and goes off to London to do her design work.
In London, Becky quickly enters into society, mostly under the guidance and patronage of Lord Steyne, an immoral, degraded, lascivious, vicious, and cruel old man, who also happens to be a Marquis (a super-high-up aristocrat) and one of the king's advisers. This guy is into Becky because she's hot, and Becky hopes to get as much out of him as she can – money, social standing, maybe even a good job for Rawdon. Rawdon doesn't really get what's going on because he's dim-witted and mostly just plays cards and gambles with Becky's other hangers-on (actually, that's where most of their income comes from). Higher and higher Becky climbs, until finally Lord Steyne's wife, the pinnacle of high society, invites her for dinner. Obviously she does it because Lord Steyne makes her, but still. This coup even gets Becky an introduction to the king of England – not bad for a broke drawing teacher's daughter.
Meanwhile, in the poor section of town, the Sedleys are doing worse and worse. For a while their money matters were OK because Jos was sending them an allowance and Amelia was putting her tiny pension from George's death into the common pot. But Mr. Sedley continues to speculate – always poorly, always losing money – until the family is actually unable to eat. Amelia doesn't realize how bad things have gotten and still does her best to deck her son out in cool duds and buy him books and things. One day, dead George's sister Miss Osborne sees this little boy out and about and is struck by how much he looks like his father. She tells Mr. Osborne about what she has seen, and Mr. Osborne starts to relent in his hard feelings. Very soon, the Osbornes make Amelia an offer to take her son and raise him (though she would get to see him). Amelia totally freaks, obviously, since she lives only for this boy.
But soon Mr. Sedley reveals that he is totally and completely bankrupt, and Amelia has no choice. Her son goes to live with Mr. Osborne, and Mr. Osborne starts financially supporting Amelia and the Sedleys. The boy grows up to be a slightly less crappy version of his father – handsome, snobby, imperious, but still somewhat kind and loving. Amelia's mom dies, then her father becomes senile and dies. Finally, Mr. Osborne dies, leaving half his property to his grandson and setting Amelia up for life pretty comfortably as well.
Becky, at the height of her awesomeness, gets the idea to put on a charade party, consisting of a bunch of mini-plays. She is of course expecting to be the belle of the ball, since she is quite the actress. She dresses up as Clytemnestra, the ancient Greek queen who killed her husband Agamemnon. Everyone agrees that she is divine and just to die for. Lord Steyne is particularly struck both by how good she is in the role and how symbolically fitting it is for her to play someone who betrayed her husband. Ho ho! The rest of the party goes great. At the end of the night, Rawdon gets Becky a carriage home and decides to take a walk. Suddenly he is arrested for debts and put into debtors' prison.
Rawdon doesn't panic, because he's been there before. All you need to do is find someone to cover your debt and then you can leave. So, in the morning he sends Becky a note asking her to round up some money and get him. The day passes, and nothing happens. Finally, in the evening, Rawdon gets a note back from Becky saying that she was not feeling well and was busy and couldn't get around to bailing him out, but that she'll get him the next day. Rawdon is furious and sends a message to Lady Jane, who comes at once. When he walks into his house, he finds Becky and Lord Steyne all alone in the living room, with wine and dessert, Becky all dressed up and singing songs to the old Marquis. Rawdon loses it completely, tears off Becky's dress and jewelry, punches Steyne in the face, and leaves.
Rawdon knows that after totally dishonoring a gentleman like Steyne the only thing he can expect from Steyne is a challenge to a duel. He goes to find a second (backup). Steyne's lawyer comes to find him, but instead of challenging him to a duel, the lawyer does some fancy talking and explains how actually the evening was totally innocent and how Steyne isn't really mad at Rawdon's honest mistake. To prove it, the lawyer shows Rawdon an article in the paper that says that Rawdon has been appointed governor of a small island in the British Empire. Crazy! A man as powerful as Steyne can make things happen.
Rawdon doesn't forgive Becky. He goes off to the island, gives his son to Pitt and Lady Jane to raise as their own, and pays Becky an allowance to stay away from him. It's unclear if she actually slept with Steyne or not, but obviously that's what everyone thinks. Becky goes from city to city in Europe, where the same thing happens each time. She makes her way into society, everyone loves her, then someone finds out her past from London acquaintances and she gets booted. This happens over and over again, and it's clear that Steyne is so angry with the way she played him that he is actually making her life a living hell from afar.
After Mr. Osborne dies, Amelia gets her son back, and she, Dobbin, Jos, and the boy decide to go to Europe to travel around. They go to the German town of Pumpernickel and have a grand old time. At a fair, Jos runs into Becky, who is now totally poor, living in kind of a squalid house but loving her Bohemian lifestyle. She immediately gets her hooks into him and Amelia, although Dobbin knows that she is bad news and tells everyone so. Dobbin finally confesses his love for Amelia, who of course knows all about it, but she tells him that she can only ever love dear dead George. Dobbin is sad and tells her that he's going away forever because after twelve years of loving her without any returned feelings, he's tired.
After he leaves, Amelia is very sad, but she's still loyal to dead George. Becky takes pity on Amelia and shows her the note that George wrote Becky about running away together the night before he went to fight Napoleon. Amelia is shocked at his betrayal but feels released from the marriage, and writes to Dobbin, who returns immediately and marries her. They go back to London, where Amelia has a daughter. Dobbin slowly falls out of love with Amelia, but continues to be nice to her nonetheless.
Rawdon dies on his island, and after Sir Pitt dies, Rawdon and Becky's son inherits the Queen's Crawley and the whole Crawley fortune. He gets to be good friends with Amelia's son and never sees his mother again. Becky and Jos travel around Europe for a while, until he dies under very mysterious circumstances and Becky tries to collect his life insurance policy. At first the insurance company denies the claim, but she hires some lawyers and the company is forced to pay, since murder cannot be proven. (But it's strongly implied that Becky poisoned Jos.) Becky ends up living in Bath with a nice income, a group of loyal friends, and a life of pious charity work.