Naan (1967)

A rich man's son gets lost at a very young age while trying to escape his father's enemy. After a few years of searching in vain for his son, the father dies. Years later, three men visit the palace, each claiming to be the prince and seeking rights to all properties. All three answer all questions related to family history. The palace management are left with no choice but to accommodate all three men unless they find the true heir. The story takes a complete U turn when it is revealed that a fourth man is the real prince, but his whereabouts are unknown. The only way to real the real prince is via these three people who know where he is.