David was sent to concentration camps in Bulgaria since childhood, not knowing who and where his parents were. He grew up in concentration camps and went through all kinds of tribulations.
When he was twelve, he was one day helped to escape from prison by a mysterious person in prison.
The mysterious man manages to help him escape from prison and hand him a letter. David was told not to open the envelope on the road, not to trust anyone, and to send the letter to Copenhagen.
He trekked alone over the mountains, through Greece, Italy, Switzerland, and Denmark.
The child on the road was terrified, and although there was peace and tranquility along the way, his heart and eyes were on the letter and on the road ahead. He insisted on going all the way, always remembering that the mysterious man did not trust anyone.
There is a very impressive scene in the film, on the picturesque top of a mountain, David meets a kind old woman painter, the old woman treats him as a grandson, gives him selfless love and great help.
In addition to that, there were many others who helped him along the way. Well-meaning people let David slowly understand the fact and truth: we should know that there are good people and bad people in the world, we can be defensive, but more importantly, we don't have to prevent others from entering our world.
With the help of people, large and small, and with David's own persistent efforts, he finally achieved a satisfactory result.