Guo Gangtang, whose son went missing 18 years ago, holds a banner with a photo of the child at the age of two, in Liaocheng, East China's Shandong province, on March 29. He has traveled around looking for the child for the past 18 years, covering 400,000 km throughout the country. His story is being adapted into a movie which will be released in January. [Photo/CFP]