We see prosecutor Lee Cha Don's past when he was actually a rich kid Lee Kang Seok. Ji Se Gwang tries to kill his dad, but he goes into coma instead. He then conspires with Eun Bi Ryeong and frames Kang Seok's mom for attempted murder.

Ji Se Gwang finally succeeds in his plan of framing Kang Seok's mom for murder. He also acquires all his property. Kang Seok comes to know about all this and so he tries to kill him. But he meets with an accident due to Bok Jane's car and reaches hospital.

Kang Seok loses his memory as well as his ability to understand anything. But slowly it's revealed that he has indeed become a genius in memorizing things. Se Gwang gets appointed as a prosecutor and he beaks up his relation with Bi Ryeong. Kang Seok finally remembers that he has mom and dad, but nothing more than that. He lives in an orphanage. Meanwhile, Bok Jae In develops a huge crush on him.

Se Kwang has now reformed into a righteous prosecutor. He doesn't accept Cha Don as his trainee. So the latter tries to prove himself by convincing Jae In to be a witness. But she takes his cojoling seriously and falls for him. But later comes to know the truth.

Lee Cha Don goes to prison. Yellow Sea Credit Union is bankrupt. Ji Se Kwang resigns and runs election for mayor. Jae In tries to oppose him in every possible manner. Finally, Cha Don is able to revoke his case and comes out of jail.

Cha don is reinstated as prosecutor. Ji Se kwang wins election, but is arrested for murder and embezzlement. Ji hoo finds out about his Swiss account.