In this holiday special, The World takes you to China. We visit Shenzhen, which has become the most thriving megacity in the world — without the air pollution, overcrowding and failing infrastructure that often accompany rapid expansion. Also, an unpacking of the latest diplomatic spat between China and Japan over Taiwan. And, a peek at the future of transportation innovation from the Automotive World China Exhibition, complete with electric cars and self-driving sanitation vehicles. Plus, the story of a mother who traveled with her adopted daughter to China in search of answers about her past.