Depressing melody, too quiet. Individual non-musical sounds are interspersed in it, such as the grinding of metal or very distant singing of the birds. The girl who acts the main part in the movie, by the voice is very similar to the performer of this song. She's beautiful and unhurried, the same as divergent itself, which in this episode of motion picture becomes insurgent. A man's voice here is very quietly starts and ends the melody in the style of pop.
Reference: Woodkid and Lykke Li Team for "Never Let You Down" From Insurgent - Read on Pitchfork
Never Let You Down lyrics - Woodkid feat. Lykke Li