Filthy is the coming-of-age story of the seventeen year-old Lena. In love with a boy for the first time, Lena longs for freedom and adventure. Her world is shattered instantly when her teacher, whom all her classmates have a crush on, rapes her in her own home. Instead of sharing her trauma, Lena keeps it a secret, even from her best friend. Her pent up feelings drive her to attempt suicide. With her family in shock, Lena ends up in a psychiatric ward.
Among wild and similarly misunderstood kids, she discovers she is not alone in her experience. But when her roommate and the only person in the ward she likes hangs herself, Lena hits the bottom. She agrees to electroconvulsive therapy. At first, it seems to help and – apart from memory loss – Lena is well again. But the attempt to live her old life does not last long. Gradually, her memories come to the surface, bringing a realization that is unbearable. This time, however, she does not fall into the same abyss of self-hate and instead tries to face the trauma.