Megapolis (2007)

In the contemporary metropolis (megapolis), there lives a common incomplete family - Tima, a 5-year-old "man", and his mother, Anna, "a lady in search". They are quite happy together, if it were not gnawing in Anna's heart - she's always seeking for a candidate to marry to. That is why, being at a street fire-show one night, she loses her son in the crowd. Tima falls into hands of juvenile homeless offenders who are making their living by dashing under cars or by blackmail. He becomes a member of their band-family and "a source of income". All that had seemed important to Anna before her son's loss now fades into the background. The only Anna's dream now is to find money for ransom. -- IMDB