Da Hei and Xiao Bai meet when moving into the same apartment together. Xiao Bai is focusing on his graduate studies along with his reconnaissance job, while Xiao Bai takes on odd jobs to fund his little sister’s medical needs. As their lives start intersecting, how will their relationship develop?

Xiao Bai learns that the place where Da Hei has been working may be a front for illegal activities, and is tasked with investigating Da Hei. Da Hei also notices Bai Zhou Qi's unusual behavior and becomes more alert. While the two of them are testing each other, Da Hei’s grandmother suddenly arrives at the apartment…

Xiao Bai takes the initiative to admit his love to Da Hei, which gradually closes the gap between them, and Da Hei begins to develop subtle feelings for Xiao Bai. However, will their feelings get in the way of their respective duties?

Xiaobai gets injured because of Dahei, and while tending to his wounds, Dahei ends up getting drunk to stop Xiaobai from drinking. This interaction leads to a change in their relationship…

While Xiaobei helps Dahei with an uncomfortable situation, Dahei gets a phone call from the hospital and needs to tend to his sister immediately, with Xiaobei going with him.

Between his mission and his emotions, Xiaobai realizes that he is starting to worry about Da Hei's safety, fearing that he will be targeted by his employer, so he asks him to terminate the operation. However, Dahei doesn't understand Xiaobai's concern at all, and instead asks him a question - are we together?

During a balloon-shooting game, Xiao Bai reveals impressive reflexes, prompting Da Hei to suspect that Xiao Bai may be hiding something. At the same time, intelligence officer Bo Xing notices that Xiao Bai’s feelings for Da Hei have become more than just professional—and issues an ultimatum. Just then, the sudden appearance of the White Zhou envoy deepens Da Hei’s doubts: Who are you, really?

Da Hei raises money for his sister’s surgery, and Xiaobai worries that he’ll become more entangled with his job. This triggers a heated argument between the two, which leads to Xiaobai hiding his identity and Da Hei keeping his issues to himself.

Da Hei is heartbroken when he sees Xiaobai having been injured while protecting himself. Xiaobai reveals his true identity which causes Da Hei to lose all trust in him; their relationship is at an impasse.

Xiaobai is brought back to his original job and punished, but doesn’t take it to heart. Da Hei seems to be rudderless without Xiaobai, but he can’t forgive the lies Xiaobai told him. Will the two be able to work through their difficulties and be together again?

Da Hei confesses his feelings to Xiaobai’s grandfather, but he cannot accept their relationship. At the same time, Xiaobai visits Da Hei’s grandmother; how will this play turn out?

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