Fourteen-year-old Rustam lives with his mother in a village; his father was killed by the Russian mafia. After his father's death, Rustam tries to provide for himself and his mother without resorting to illegal money-making schemes. But his dream is to join a music band. The title of the film refers to an Azerbaijani fairy tale about saving a princess from a house with 40 doors; no one has succeeded in opening the last door, and thus its secret remains hidden. The villagers have named their village the 40th door as well.

Living alone, Jamal is a painter, but no one likes his works, which causes him great depression. He has a self-righteous fiancée named Lala. One day, his friend Adalat comes to Jamal's house in the middle of the night drunk with a bar girl, Zara. Adalat asks Jamal to stay at her house for one night. However, when morning comes, Adalat does not come after the girl. When Zara wakes up, she thinks that Jamal brought her home. Thus, sublime feelings arise between people from different worlds.