A woman tries to commit suicide by jumping off a bridge, but Kim Do-gi saves her in the nick of time. She tells him her tragic story and asks for help to get revenge.
With an eye on payback, Do-gi transforms into a deep-pocketed customer to trick Kang Maria's tormentors; Kang Ha-na wonders about a missing criminal.
Ha-na interrogates Sung-chul regarding the missing taxi and discovers something shocking about his past; Do-gi disguises himself as a substitute teacher to help a high school boy get revenge on his bullies.
The three bullies attempt to take down Do-gi but stop when they learn that he has a video footage that could destroy their lives.
Do-gi wakes up in the hospital after passing out on the streets; Ha-na pays a visit to Mr Jang to talk about something; Do-gi obtains Seo Young-min's files and Ha-na intends to work on the same case, despite Jin-woo's warning.
Do-gi starts working at U Data and discovers something shocking; Do-gi plans to transfer to Strategic Planning Team; Chairman Park puts Do-gi's loyalty to the test.
Lee Je-hoon
Kim Dogi
Eui-sung Kim
Jang Seongcheol
Pyo Ye-jin
Ahn Go-eun
Jang Hyeok-jin
Choi Gyeong-gu
Bae Yoo-ram
Park Jin-eon