For eighteen years, Lin Yingchun's father came home for only seven days each year, during the Spring Festival. Afterward, he returned to the mysterious Northwest Aerospace Experimental Base to work in isolation. While there, he could neither go out nor communicate with the outside world, as if he had vanished completely. Lin Yingchun didn't believe her father really did that kind of work. She suspected it was all a lie, and even thought her father had betrayed the family. To find out the truth, Lin Yingchun lied to her mother, saying she was going on a trip to the northwest with her cousin. In reality, she secretly set out on a journey of a thousand miles to find her father. But when she finally reached the Northwest Aerospace Experimental Base her father had told her about, she discovered that things were not as simple as she had imagined... What secret had her father kept for eighteen years?