Nigel Dobson (Hugh Grant) and his wife Fiona (Kristn Scott Thomas) are a perfectly respectable British couple with nuances of gentlemanly life. They are on a cruise during their honeymoon heading for India. They meet an extremely sensual young woman of French origin called Mimi (Emmanuelle Seigner), extremeley flamboyant and Paris-cosmopolitan, and by means of her they come to meet American wanna-be author Oscar (Peter Coyote), a disabled man in a wheelchair. Oscar starts telling their love story to Nigel and Fiona. The latter finds it gruesome and unsettling, and doesn't want to know how it ends, but Nigel will become completely obsessed with the love-hate story of Mimi and Oscar.
Oscar finds in Mimi, a student dancer, a willing partner for his almost hardcore sexual games, ever pushing their boundaries together. She is completely enraptured by him, and bows to his every whim. However, without any furthr reason that his caprice, he gets bored out of his wits about her. He is rude and wicked to her, and tells her that he'd rather she left him for good. Mimi packs her things, and is about to leave him forever. She has opened the door to the condo where they have been living together, but re-enters the flat again. She wants to stay no matter what.
Life will be hell for Mimi from that moment on. He becomes really abusive towards her, and she puts up with everything. Their sexual antics become sadistic, full of anger and twisted mentality. I agree with some other reviewers into saying that Mimi becames a mere shadow of her former self. She has stayed with him, but life becomes a nightmare. She mus quit all her life and interests in order to pursue her obsesive love for him.
She has to do things she doesn't really want to because if not, Oscar will sent her packing for good, and she knows this time there won't be a second chance. Finally, she becomes pregnant, and that's a door for her to lead a normal couple life with Oscar. They agree to leave France together and keep the child. However, Oscar's behaviour is selfish and rotten once more. He pretends to follow-suit her, but when they are both on the plane to Martinique, he leaves the plane with some dumb excuse. Mimi is completely distraught, and the audience will come to know what she did afterwards. She had an abbortion performed by some doctor who butchered her, and had to surpass a terrible infection on her own. The surgery and its consequences have left her uncapable of getting pregnant again, and that comes to a shock to her as well.
Meanwhile, Oscar returns to his happy life: he goes to parties, gets drunk, and has sexual relations with all sorts of women. He doesn't seem to write much. Once, he is so drunk that he suffers a car accident which will leave him crippled for life. Mimi returns to Paris because, after all, her traumatic experiences have not made her to forget him. She won't forgive him, but the audience will come to know how much she loves him in spite of it all. She has become frustrated, angry, and wants revenge for everything Oscar has made he go through despite her love. She takes care of him, but in a twisted and cruel way. She doesn't allow him to talk to any of her former lovers, or go out of home without her. One of the prevert things she did is to hold a long conversation leavin Oscar in the full-of-water bath. While she's talking gayly, the water gets colder and colder, so Oscar has to leave the bathroom crawling like a worm. Mimi sees this with a half-smile onto her lips, and keeps on chatting as though without a care in the world. On another occassion, she gives him a present: a gun with a single bullet so that he can commit suicide.
Coming back to the crouse, Fiona gets utterly fed-up of Nigel. She is afraid that he wants to have sex with Mimi, because she's constantly flirting with and giving hints to him. She tells him that she can do anything better than him, so she starts flirting with Dado (Luca Vellani) during Oscar's story sessions.
Nigel looks for Fiona, and to his surprise, she finds her in bed after having made love with Mimi. Oscar had watched them while having sex. Both women are sleeping in a hug, and he shoots Mimi. Fiona is woken up because to the noise, and Nigel and Fiona leave the cabin together, deeply traumatized because of everything they have witnessed.