The Great Ambition (2002)

Left on his father's doorstep as a newborn, Park Jae Young grows into a warm-hearted though naive person, quite unlike his scheming and ruthless father and elder brother, Park Si Young. He shares an innocent first love with Yoon Yeo Jin, who he has known since childhood and is a member of the aristocratic class. But when he is faced with his family's murderous methods, Park Jae Young runs away from home. He then meets Choi Dong Hee and her merchant father, and reunites with his mother, now a powerful political power. Can a good but naive man help support the rightful next emperor, or will his brother's evil plans succeed?