Jiang Xingyao returns to the long-unused old mountaintop observatory to prepare for the final inspection work before sealing, only to find abnormal observation data in the old telescope records. Together with retired mechanic Gu Chengshan and data engineer Shen Yubai, she investigates. From equipment failure to observation records, they gradually restore the story hidden within the old dome. As the telescope starts running again, the three of them also face past regrets and unfulfilled promises during the process of repairing the equipment, letting the starlight that has been silent for many years illuminate the old observatory once more.