The movie starts off with "The Businessman" (Bill Murray) in a cab racing through the streets of India. He gets to the train station and sees his train leaving. He takes off after it. As he's running, he's suddenly passed by Peter (Adrien Brody). Peter is able to outrun the businessman even though he is carrying several pieces of monogramed, (but not with his initials - important later), luggage. He throws the luggage on the train and gets on.
Peter gets to his compartment where he meets his brother Jack (Jason Schwartzman). Jack is a writer and throughout the movie he keeps asking his brothers to read his work. They claim that his pieces are based on things that really happened, (saying things like: "You really captured your anger here"), while Jack argues they are really fiction. Francis (Owen Wilson), the third brother and oldest then shows up. His face is bandaged and he tells the brothers that he crashed his motorcycle into a hill. Initially, he makes it sound like an accident, but by the end of the movie he confesses he did it on purpose. At this point, the brothers have a matching pile of the monogrammed luggage. It comes out that they have not spoken in a year. Peter is wearing their late father's sunglasses even though they are not the right prescription and carrying the father's car keys. The other brothers are more upset because they have decided they want those things and not because what Peter is doing is strange.
All three brothers start smoking in their compartment and the chief steward tells them there is no smoking. They go to dinner. While there, Francis picks orders for everyone, (important later). The other two object, but ultimately go along with what Francis said.
Francis tells them they have a set schedule for every day that will be delivered by his assistant who Francis had bring along a printer and laminating machine. The brothers have also all bought over the counter Indian pain medications, (suggested they are very strong), and they share these.
Jack confesses to Peter that he has his own return ticket so he can leave the trip early. Peter tells Jack his wife is pregnant and that he came on this trip without telling her. Jack meets up with their female steward, Rita, and they have sex. Jack pursues Rita, but she is more reluctant. It comes out later she is dating the head steward.
At the first stop, Peter buys a poisonous snake. Francis stops to get his shoes shined and has one shoe stolen, (It is suggested throughout the movie that he is very wealthy - he does something in Hollywood). Jack buys pepper spray.
When they get back on the train, the snake escapes and they have to call the head steward for help. He catches the snake, but is very angry with them and threatens to throw them off the train. He finally agrees to let them stay as long as they stay in their cabin.
Later that night, all the secrets come out. (Francis' secret is that he arranged the trip so that they could all meet up with their mother who left them years before. He gets a letter at some point from her telling them not to come because there is a man eating tiger on the loose by her convent, but he is not dissuaded). Francis and Peter start to get in a fist fight. Jack tries to break them up with the pepper spray. The three run around the train, before one of them, (I think Jack), runs into a plate glass window, breaking it. The steward sees and throws them, (and their luggage), off the train. -- I didn't do justice to this scene AT ALL, but it was hilarious. Best part of the movie.
Francis' assistant is getting off the train with them, but Francis insults him. As a result, he thrusts the printer and laminating machine at the brothers and gets back on the train. They are alone.
It's the middle of the night, so they camp out. They try to do a ceremony that Francis found out about to bring them closer - it involves peacock feathers and praying and going off by themselves. Francis tells them to keep the feathers so that they can bury them together, but Jack and Peter accidentally let go of theirs.
The next day they are walking along a river with all of their luggage when they see three young boys trying to cross. The boys' raft capsizes and they are all swept into the rushing water. The brothers jump in to try and save them. Francis and Jack are successful, but Peter's boy dies, (he keeps repeating this). The brothers take the two living boys and the dead boy back to their village, (Peter carries the dead boy). The boys explain what happened and the villagers care for the brothers' injuries while everyone mourns.
The next day, one of the boys takes them to a place where they can catch a bus to the airport. They get on and have all their luggage on top when the other boy runs up and invites them to the funeral. They decide to go. They are dressed in all white mourning clothes and riding in a small bike-driven cab. There is a flashback to them all in a limo dressed in black going to their father's funeral. On the way, Peter tells them to stop so he can pick up their father's porsche from the shop it is in (this is where the keys from earlier in the movie come in). The others try to dissuade him, (his wife is also in the limo, so we meet her there). The other brothers insist on going too in case there is a missing piece of the monogrammed luggage in the truck, (this is where it comes out that the luggage belonged to their father). The engine on the car isn't fixed, so despite Peter's efforts, they can't get it started. They finally have to give up and go to the funeral.
The movie cuts back to the young boy's funeral. Afterwards, the brothers go back and get on the bus. The whole village, (it seems), is there to see them off and express their gratitude.
The brothers go to the airport to go home. While there, it comes out that Peter's wife had the baby. She is not happy with him. Peter is more excited now.
The brothers are about to board the plane when they decide that, because they have now made piece with each other, they should go find their mother. They destroy their tickets and set out, (with the luggage). Their mother's convent is set high in the mountains.
When they get there, their mother, (Anjelica Huston), comes out to meet them. She scolds them and says she told them not to come, (it turns out the man eating tiger is real), but she is very happy to see them. That night, as they get ready for bed, she tells them, (mirroring what Francis did earlier in the movie), what they will all have to eat in the morning. She goes to leave, but before she can, the brothers all express resentment towards her for leaving them, (Francis had to use a private investigator to find her the first time), and for not coming to their father's funeral. She tells them they shouldn't have come, but they seem to end things on a good note. However, when they wake up, she has left again, but she did leave breakfast.
The brothers go out with the last feather and complete the ceremony correctly.
When they return to civilization, they are shown in a cab going to the train station. Jack reads a new story which is clearly about what has happened to them. The brothers comment on this, (but say how good it is), and Jack admits that he did base it on reality.
When they get to the train station, their train is leaving. They run after it, (with stewards following with most of the luggage). As they run, they look at each other and throw down all of the luggage they themselves are carrying and run faster. Because they don't have the luggage, they are all able to jump on the train, leaving all the luggage behind at the train station.