Fifteen years ago, Leo's mother Lina perished in a massive fire. Leo discovers that Lina had worked as the personal assistant to Edward, CEO of the Evans Group, and the two had been intimately involved. Convinced that Edward is his mother's murderer, Leo also suspects he might be Edward's illegitimate son.
Fifteen years later, Leo infiltrates the corporation under a false identity and becomes the secretary to Ethan, Edward’s son. On his very first day at work, Ethan mistakes Leo for an escort he had arranged. The two end up having a one‑night stand by accident. Leo flees in a panic and leaves behind his mother's necklace.
Using his position, Leo investigates the truth. Yet as he spends more time with Ethan, he gradually falls in love with him. Edward soon detects Leo's presence. He sees Leo as worthless leftover baggage left by Lina and grows contemptuous, even plotting to have him killed. Trapped under his father's control for thirty years, Ethan has never dared to rebel — until he learns of his father's plot against Leo. For the very first time in his life, he chooses to defy Edward.
In the end, Leo and Ethan join forces to bring Edward down. A DNA test proves Leo is not Edward’s biological son. Having overcome all obstacles, the two finally find happiness together.
