Cahit is a middle-aged widower of Turkish origin living in Hamburg who keeps his demons at bay by pursuing Punk-induced slovenliness as a lifestyle choice. Sibel is a hedonistic young Turkish girl desperate to protect her own way of life from the traditional mores of her father and brother.
They meet in a mental institution after separate episodes of self-harm and she proposes a marriage of convenience. Living as room-mates they both pursue their carnal interests elsewhere, but the stability of their relationship is gradually compromised by a domestic bliss that evolves from affection through desire and onto jealousy.
It's easier to see how Cahit makes this transition than his wife, because at first she seems quite oblivious to his inner world.
Each section of their story is separated by a transition in which a line of musicians plays soulful Turkish music with the Istanbul skyline behind them. I found the last of these acts the least satisfactory, because I felt that writer-director Fatih Akin had attempted to explore so many different themes of exile and clashing values that he'd lost sight of the personal story at the heart of his movie.
This unfortunately culminates in a cinematic cliché, but overall the film is thoroughly gripping, as well as being occasionally quite startling. It has a definite edgy quality, deriving I think from the fact that there are so many alternative ways that the phoney wedlock situation might have been resolved.