Mok Sol-hee, "Liar Hunter", has a special ability to distinguish between truth and lies. She runs a secretive tarot café where she receives requests from VIPs who need her ability. One day, top composer Kim Do-ha, hiding from a dating scandal, moves into her neighborhood. When he's nearly exposed, Sol-hee helps him—but Do-ha, recognizing her from five years ago.

In a moment of crisis, Do-ha escapes the situation with Sol-hee's help. Now, Do-ha remembers Sol-hee, whom he briefly met five years ago in his hometown, and is anxious about whether she recognizes him. Unfortunately, the two end up as next-door neighbors. Sol-hee grows curious about Do-ha, who avoids people and never lies. Sol-hee receives a new request.

As Sol-hee learns Do-ha's real identity, she feels sorry for Do-ha, who always hides himself under a mask. Do-ha avoids her, as he's afraid that Sol-hee will recognize him. Since Sol-hee misunderstands that he’s avoiding home because of her, she tries to apologize. While Do-ha starts to get curious about Sol-hee, a suspicious man appears, claiming to be Do-ha's friend.

To protect Do-ha, Sol-hee pretends to be his girlfriend. They finally get to know each other’s real names, but Sol-hee begins to doubt Do-ha's honesty. Oddly, her lie-detecting ability doesn’t react to him, so Sol-hee begins to wonder if her ability doesn't work for Do-ha. She tries to induce him to tell a lie, and suddenly, an urgent phone call comes in from someone looking for Do-ha.

Do-ha falls ill after saving Shaon from the ocean. Sol-hee nurses him, but his past trauma surfaces and he lashes out, hurting her. Their relationship becomes awkward again. Though she realizes he’s not her fated match, she remains unsettled—especially when Do-ha disappears without a word, and someone claiming to be him uploads a video exposing himself.

As a token of gratitude, Do-ha treats Sol-hee to a nice meal, eventually creating a subtle dating atmosphere. The two get closer with the help of alcohol, having a deep conversation together. That night, Sol-hee gets drunk and makes a big mistake. Meanwhile, Eom-ho, out of prison, threatens to expose Do-ha’s identity to Deuk-chan.