Five years ago, Su Qingwan rescued a distressed Ye Beichen on a rainy night, but long since forgot. Five years later, the two reunite in an unexpected accident. Ye Beichen hides his true identity, staying by her side as an ordinary security guard to accompany her through workplace crises and successive tests. Through getting along, the two go from mutual help to mutual trust, and their feelings quietly warm up. Until Ye Beichen's true identity is uncovered, Su Qingwan finally understands that his years of guarding have long been more than just repaying a favor. In the end, the two grow individually and finally choose to move forward side by side.