A simple honk（汽车喇叭声）from the bus is one part of a secret code（秘密代码）between the driver and students living in a far-away village in Wanzhou district, Chongqing. Seeing a schoolbag hanging from the doorknob of an old house along the road, the bus driver drives toward the roadside and makes a honk to answer the "code". Then a boy runs outside, takes the schoolbag, and gets on the bus.
The boy's parents work far from home, leaving him in the care of his grandmother. The boy is in the ninth grade this year. He comes home every Friday and goes back to school in the city every Sunday. To make the journey easier, he and the driver, Cheng Lin, have developed a special "code". When the boy's schoolbag is hanging outside the house, it "tells" Mr Cheng, "Today, it's time to go back to school. I need to catch the bus. "The parents of the boy are deeply moved（感动）to hear this.
Mr Cheng has been driving the Luotian to Wugiao Nan Station bus for many years. There are many left-behind children on this bus line. Knowing the importance of his role in their lives, he has paid more attention on Fridays and Sundays.
