Yeon Ju is an elite prosecutor, and her goal is to become a chief prosecutor. Therefore, she wants to investigate and catch the fraud that the deputy chief of her division failed to. Meanwhile, Mi Na is left out of her family and in-laws just like any other day and attends an art auction alone. As they are fated to, Yeon Ju sees Mi Na and gets shocked as she looks exactly like her.

When Yeon Ju wakes up at the hospital, the doctor tells her that she has retrograde amnesia due to a car accident. Yeon Ju is thrilled to find out that she is part of a wealthy family, but at the same time, she feels suffocated when she is around her in-laws. While she's feeling gloomy that no one in her family actually cares about her, she meets Seung Wook.

After Yeon Ju threw a fist towards her in-laws at the remembrance service, a rumor spreads about Yumin Group’s heiress having a psychological problem. Sung Hye takes this as an opportunity, and she holds an emergency shareholders’ meeting to impede her from getting an inheritance. Meanwhile, Hanju family gets shocked to find out the major shareholder of the Yumin group.

Yeon Ju realizes that she is involved with a gang, and she decides to hide this from Hanju family. However, when she gets arrested on suspicion of drug use, she also notices that she is extremely smart and familiar with law sections. Meanwhile, Seung Duk decides to look for Yeon Ju himself as she has been away for way too long.

With her critical thinking and analytical skills as a prosecutor, Yeon Ju does her job as the new chairman of Yumin Group smoothly even though it is her first day. And Seung Wook finds out that Yeon Ju and Mi Na's accident is not coincidental. Meanwhile, Sung Hye figures out that Mi Na took the paintings before the car accident and starts to suspect her.

Yeon Ju and Seung Wook share their personal stories and spend time together often to figure out where Mi Na is. However, Seung Wook realizes the more he gets to know about Yeon Ju, she reminds him of Mi Na. Meanwhile, Sung Hye asks Yeon Ju to unlock Mi Na’s tablet in front of the whole family.

Yeon Ju has no choice but to visit the prosecutors' office to be questioned by Yu Jun since she got caught faking her acute stomach cramps. However, the brake of the car she is driving is not working, and she is about to get into huge trouble. Meanwhile, Yu Jun finally meets Yeon Ju and tells her about her true identity.

After Bong Sik finds out that Yeon Ju is living a double life as a prosecutor and the chairman of Yumin Group, he secretly tracks her down. Fortunately, Yeon Ju regains her memory and tries to persuade Bong Sik to take her side. Meanwhile, the more Seung Wook gets to know about Yeon Ju, he gets attached to her.

Now that Bong Sik is dead, there is no one to prove that the list was fabricated. Therefore, Seung Duk wants to end the case with Mi Na to hide his crime. Furthermore, Sung Hye puts the blame on Yeon Ju for the reorganization of Hanju Hotel and the fired workers carry out a demonstration. Meanwhile, Seung Wook makes a deal with his uncle, Young Sik, to save Yeon Ju.

Seung Wook realizes that the girl he met 14 years ago was Yeon Ju, not Mi Na. Yeon Ju rushes to Hanju Hotel to see Seung Wook, and they admit they both have feelings for each other. Meanwhile, Yeon Ju and Sung Hye look for the flash drive Bong Sik had hidden before he died, and Yeon Ju and Yu Jun believe that Hanju Group has connections with Samgeori Gang.

Yeon Ju and Seung Wook hear all the details about the fire at the Hanju Fashion factory 14 years from Myung Guk. Yeon Ju learns that Myung Guk was innocent after all and decides to help him clear his name, despite her mixed feelings. Meanwhile, Sung Hye puts pressure on Sung Woon to get information on Yeon Ju.

Sung Hye flies into a fit of fury when DNA results say that Yeon Ju is Kang Jang Soo's biological daughter. When Young Sik tells her to lie low for the time being, Sung Hye decides she must go about things differently to get her own way. Meanwhile, Yeon Ju sets up an investigation headquarters at Seung Wook's place. She plans a counterattack against Seung Duk.

When Yeon Ju finds out the culprit of Hanju Factory accident was Sung Hye, she warns her that she'll pay for her sin no matter what. However, Seung Duk betrays Young Sik and turns to Sung Hye instead, and Young Sik gets arrested for his crime. Meanwhile, Sung Hye starts to look for the person who has real Mi Na's DNA samples.

Yeon Ju and Seung Wook succeed in taking Mi Na away from Sung Hye and Samgeori Gang, but Yeon Ju gets arrested. Mi Na tells Yeon Ju that Sung Hye has another secret that no one knows about, and they need to reveal it to bring her down. However, when Seung Wook tries to get her out, Seung Duk takes the chance and fires her, and Sung Hye secretly meets Hak Tae to get back at Yeon Ju.

It is too late when Yeon Ju realizes Hak Tae switched his side to Sung Hye's, and her team fails to arrest Sung Hye at her inauguration. Yeon Ju is confused and upset with Hak Tae and decides to meet him personally, but he secretly puts something in her drink. Meanwhile, Mi Na wakes up and visits her in-laws to reveal Sung Hye's most brutal crime of all.