All Longing, Farewell

Premise

In the 1980s, Cheng Hai is a top expert in precision technology who stays on as chief engineer at the struggling Hongxing Machinery Factory. He does it to repay his mentor's kindness and to help the young factory director, Zhong Lin. For three years he works through countless hardships and turns the factory into a leading name in its local industry. The story opens on the strength of that partnership and the work they share.

Characters

Cheng Hai is the engineer whose loyalty to his mentor keeps him at a failing factory long after he could have left. He carries the technical weight of the company on his shoulders. Zhong Lin is the young factory director who depends on him and later comes to understand what he lost. The new college graduate who replaces Cheng Hai on his own R&D team represents the change that pushes him out. The mentor who asked him to help is the reason he stays in the first place, and that debt shapes every decision Cheng Hai makes.

Main arc

The turning point arrives when Cheng Hai leads his R&D team back to the factory and finds himself replaced by a new college graduate. With only seven days left before his three-year promise expires, he leaves as soon as the term ends. Zhong Lin does not realize the full meaning of that departure until it is too late. Consumed by regret, Zhong Lin tries to win him back, but the two have already drifted apart and have become strangers to each other. The arc is a study of what happens when a bond is taken for granted and then discovered too late.

Themes & tropes

The show's emotional core is regret and the cost of misjudging the people who help you. Second Chance is the idea the story keeps circling, though it arrives too late to restore what was lost. Betrayal fits the moment when Cheng Hai is pushed aside for someone newer, even if the synopsis frames it more as a loss of standing than a deliberate betrayal. The period setting gives the story a grounded, workplace feel, and the focus on engineering and factory life distinguishes it from the romance-heavy titles on the platform.

Why viewers watch

Viewers who like slow, adult workplace drama will find a different kind of appeal here. The story is less about flashy twists and more about loyalty, duty, and the quiet ways people fail one another. The 1980s factory backdrop gives the show a distinct texture, and the regret that closes the gap between Cheng Hai and Zhong Lin lands harder because the two men were once so close. At 83 episodes the show has room to let that gradual distance feel real.