Moulin Rouge is a movie musical in which a young Obi Wan Kenobi learns a hard lesson about love from the only wife of Tom Cruise not a completely batshit insane Scientologist. All whlie singing and dancing to remade oldies music.
The year is 1899. Christian (Ewan McGregor) a naive writer decides to move to Paris to see if he could try and get himself known. He runs into a group of musicians who are trying to write a play called "Spectacular! Spectacular!" Yes this is a movie/musical about writing and then performing a play loosely based on the events of the musical. This is where we would normally stop caring but the very next scene is all the characters getting bombed on Absinthe and seeing Kylie Minogue flying around as a green fairy.
After all of that the troupe decides to send Christian to the Moulin Rouge, which is basically a high end whore house, to talk to the manager to see if they would be at all interested in producing the play that they kind of have written but not really. While Christian is there he sees the lovely (see also: large chested) Satine, one of the "performers" at the Moulin Rouge, and immediately falls in love with her because that's how things work in musicals.
Meanwhile The Duke, (who is not John Wayne much to our dismay) a wealthy patron of said whore house, and the new main financial supporter of the Moulin Rouge, tells the manager of the Moulin Rouge, Mr. Zidler, that he would like to get Satine in a room alone to seal the deal.
Mr. Zidler, who admits that without The Duke's money they will go bankrupt, ends up convincing Satine to sleep with The Duke by promising her a whole bunch of the money that they will be getting once The Duke is officially their sponsor. Being a filthy dirty whore who doesn't believe in love she agrees. Satine is told to go to her room after her performance that night and wait for The Duke to arrive.
Christian, still trying to find someone to pitch the play to, ends up following Satine to her room. When he enters Satine immediately assumes that Christian is The Duke and forces herself on him while he runs around the room like a sissy insisting that he's only there to pitch the script. Since she believes that Christian is going to be paying her no matter what she decides to let him pitch his idea. A medley of songs later Satine, who has always believed love is just something that you pretend to do to get men to pay you more to let them stick their ding-a-ling in your hoo-ha, falls madly in love with Christian... you hear that guys? All you need to do to make a whore fall in love with you and not make you pay for sex is sing to her. It's foolproof.
At this point they start to get intimate. Well by intimate we mean kiss. Only to be interrupted by the real Duke and Mr. Zidler. Not at all happy to see his paid for dick slave in the hands of another man he immediately asks what's going on. Christian quickly comes up with an excuse. They were obviously practicing for the new play and wanted to make sure that they had everything correct before showing it to the Duke for approval. He basically throws the whole idea of the play that was written out and makes up something off the top of his head about a penniless sitar player who falls madly in love with a courtesan. But there is an evil Maharaja who wants to take her for himself but in the end true love wins out and in the end the courtesan chooses to be with the sitar player even though he has no money because love is stronger than everything. The Maharaja... I mean Duke, being slightly smarter than a loaf of bread. Agrees to finance the play and to turn the Moulin Rouge into a theater. Satine avoids getting stuffed with Duke sausage by insisting that Christian and her keep "rehearsing" to make sure that they perform their best *wink.*
So on to a montage of remodeling the Moulin Rouge into a theater, and Christian and Satine "rehearsing" and avoiding having their relationship found out by the Duke. If the Duke ever found out about their relationship he would surely stop financing the Moulin Rouge and they would most certainly have to close their doors. Since they can't say they love each other in public they write a song into the play that whenever they sing it, they're reminded them of their love for each other.
The night before the play they do a dress rehearsal for The Duke during which another jealous whore tells The Duke that the play is exactly the same as his situation with Satine. Finally understanding what's going on The Duke insists that the play be changed so that the courtesan chooses the Maharaja over the penniless sitar player and that they remove the secret song. He further says that Satine must spend that night with him or he will no longer financially support the Moulin Rouge.
During a sexy tango done to the tune of Roxanne by The Police, The Duke attempts to seduce Satine and at the end she rejects him because she loves Christian. At which point The Duke attempts to rape Satine but unfortunately he is stopped by one of Satine's fellow prostitutes before there's any nudity. This obviously angers The Duke and says that he will kill Christian and force Satine to only be with him. Satine is brought to her room suddenly sick. No not because she was just about raped by someone who looks like this:
but because she is dying of consumption. Zidler tells Satine that she must make Christian believe that she no longer loves him to prevent him from going to the play because The Duke would most certainly kill him if he showed up. Satine does just that. Tells him that she was just stringing him along the whole time and that there was no way that she could possible love him as poor as he is. He's so hurt that he decides to not go to the play and wallow in his sorrow.
That is until one of the guys from the troupe tells him the situation that Satine really loves him and there is nothing more powerful than love. While this doesn't convince him that Satine loves him it does convince him to go to the Moulin Rouge to "pay for his whore."
The play has already started by the time he gets there. It's already past the part where the Maharaja has claimed the courtesan as his own. It's apparently about to go to the wedding when Christian shows up. Through an odd set of coincidences the actor who was playing the sitar player gets knocked out and while Christian is begging Satine to take his money it comes time for her to go on stage. The door opens that was hiding her from the audience while Christian is on his knees telling her to take the money for her services. The other actors play it off as Christian is the sitar player in disguise. Christian throws the money at Satine and walks off. All of a sudden one of the actors yells "The greatest thing you'll ever learn is just to love and be loved in return." At this time Satine starts singing the secret song stopping Christian in his tracks. He starts singing along and runs back to her. This deeply upsets The Duke and he pulls a gun on Christian but since he's a bumbling fool he drops it on stage and it eventually gets kicked out a window and he runs out of the theater. Christian and Satine kiss and it's happily ever after... Wait... no it isn't. Satine is still dying of consumption and faints and dies right there on stage while Christian cries his eyes out. The closing scene is Christian writing the story about him Satine and the Moulin Rouge.
I guess the moral is don't fall in love the second you do other people will try at nothing to split you apart try and kill you if you try and get back together and if you do manage to get through all of that one of you is going to die and leave the other alone.