What's up with the ending, indeed. Usually Shmoop uses this section to do a little song and dance about what the end of the novel means. But honestly, this time around we're thinking we've got to first spell out what even happens at the end.
So there are many, many 19th-century novels whose plot turns on a financial transaction of some sort. In almost all of them, even if the money isn't the main scene of the action, it's definitely up there in terms of level of story importance. Sometimes a young protagonist needs moolah fast, so the author offs a rich relative or two (for example, Jane Eyre's windfall from some random long-lost uncle). Or Dickens might need the protagonist to suddenly go broke, so the plot calls for some investment shenanigans (check out Gaskell's Cranford, where a bank goes bust and bankrupts a whole town). Basically what we're saying is that money is always important in Victorian fiction. Victorian authors were deeply interested in how wealth flowed from one person to another, how it was made and lost, and how having or not having it changed lives. It's no different in Little Dorrit. We've even got some of the same elements: the crazy money-from-the-sky moment as Dorrit inherits a fortune, and the investor Ponzi-scheme fraud that explodes the economy as Merdle is discovered to be Bernie Madoff's twin. (Well, a fictional twin living almost two hundred years earlier.)
But at the heart of the ending is another inheritance plot that takes some fine-combed sleuthing to figure out. Everyone ready? Take a deep breath, and here we go. A long time ago, we've got Mr. Clennam. He loves a chorus girl and they kinda-sorta get married and have baby Arthur. OK, so far, so good. But, Mr. Clennam has a rich Uncle Gilbert, who isn't into this chorus-girl marriage. Uncle Gilbert bullies weak and pathetic Mr. Clennam into ditching the chorus girl and marrying the pointy stick who becomes the Mrs. Clennam we all know and love (i.e., fear and detest). Boo-hiss! Mrs. Clennam finds out about baby Arthur and is way angry. She demands to raise Arthur as her own child and to never let him see his real chorus-girl-mommy. Not as revenge, of course, just punishment for the crime of…something or other. She's nuts. Are you with us so far? It's getting a little kooky.
Chorus-girl-mommy dies of grief and despair after writing rich Uncle Gilbert about how sad she is. Uncle Gilbert is sad and remorseful, but it's too late. (Because chorus-girl-mommy is dead. Keep up, guys.) Uncle Gilbert figures out that the one person who's ever been nice to chorus-girl-mommy was Frederick Dorrit (Amy Dorrit's uncle), who befriended her before she met Mr. Clennam in the first place. So Uncle Gilbert's solution is…a totally crazy one. For some reason, rich Uncle Gilbert changes his will to leave all his rich-uncle money to the youngest daughter of chorus-girl-mommy's friend Frederick Dorrit. What?!? And since Frederick Dorrit doesn't have kids, it's actually his brother's youngest daughter (a.k.a. Amy Dorrit, a.k.a. Little Dorrit) who stands to inherit. Wow, that's pretty convoluted.
But it's not over yet! Rich uncle leaves the changed will with Mrs. Clennam. She hides it away somewhere in the house, then makes herself wheelchair-bound and can't get to it anymore. When rich uncle dies, this newest will never turns up, and the Clennams inherit all the rich-uncle money. Got it?
OK, here we go – last stretch. Flintwinch finds the will and gives it to his twin brother. Twin brother takes it to Antwerp, where one of his drinking buddies is Monsieur Rigaud/Blandois. Twin brother spills the beans to Monsieur Rigaud/Blandois. Rigaud/Blandois steals the will, makes his way back to London, and tries to blackmail Mrs. Clennam. Mrs. Clennam finally cracks and fesses up to Amy Dorrit. Amy Dorrit doesn't want Arthur to be put off by her being wealthy, so she burns the will, forfeits the money, and gets the guy. Whew. Yeah. (Oh, and that last bit about forfeiting the easy money? That's pretty good as one of the novel's main points.)
Don't feel bad if you didn't get all of this from the novel itself – you're not alone. Especially since the big reveal of all of this is just a couple of convoluted paragraphs in the next-to-last chapter. In fact, so many people were so confused that Dickens had to add a little note to the novel explaining the whole thing.