Watch Dream Journey 4: Biography of the Demon for Free: How to Stream the Movie Online at 123Movies. . On their journey to the west, Tang Seng and Sun Wukong have a falling out and set out a challenge for each other. Sun Wukong agrees to give Tang Seng his magical powers in exchange for Tang Seng's appearance and learning. The challenge they set is to bypass the Seven Spider Sisters and defeat the Hundred-eyed Demon Lord within seven days. After the swap, who will have the determination and wit to win this challenge?