Season 1 of She Knows Everything premiered on July 8, 2020.

After working as Miss Lee at Goong Real Estates 17 years ago, Lee Goong Bok is now a real estate expert with an apartment in Seoul and owns a shopping district. However, she is having a difficult time due to the aftermath of Goong Real Estates president's son Seo Tae Hwa's incident. Tae Hwa grew up with Yang Su Jin, a girl of a mysterious death, during his childhood years in Goong Apartments. Su Jin was found dead a day after Tae Hwa confessed his feelings for her and got rejected. Miss Lee tries to cover up her death, regardless of whether it was murder or suicide, to get Goong Apartments reconstruction approved. Miss Lee and veteran detective In Ho Chul dig to uncover the truth behind Yang Su Jin's death while chasing after suspects and confronting everything in their way.