Need help to find a specific movie

Hey, r/movies. I've been lurking for quiet some time now, I love this subreddit. I have come across one problem, though. There's a movie, I saw on the television few years back, but I never got its name:

It's about a young boy, who lives with his mother and her boyfriend, whom he dislikes. The boy gets sent to 2 old men (I think one of them is his grandad). These 2 live together in the country, and one of them tells this story about how he became so rich when he was in Serbia or a country like that. Turns out these men had a lion in a cage near their house. I remember one of the old men found his treasure that he had hidden all these years, at the end of the movie. And when the boy, some years older, comes back to their house, they've died of crashing the plane into the house.

I'd love to this movie again, and I really hope you guys can help me! :)