A family drama with spy thriller elements, it starred Kim Jae-joong as a genius analyst working for the National Intelligence Service (NIS), while Bae Jong-ok played his mother, an ex-spy from North Korea.

Soo-yeon argues that she doesn't know much but she is willing to cooperate and in exchange begs for the NIS agents to save her family by helping them escape from North Korea.

While mom sits in on Young-seo's class, Ki-chul calls the cellphone he secretly left in her handbag.

Mom is shocked to learn from Ki-chul that her son is not a simple government employee but an exceptional field agent of the NIS.

Sun-woo discovered that the interrogation process has ceased, and Soo-yeon, the North Korean agent will speak out in a press conference tomorrow morning.

Song calls a meeting, Sun-woo's plan is to turn Soo-yeon into a double agent and send her back out into the field.

Sun-woo conveys the double agent idea to Soo-yeon, who agrees as long as she can get enough money to resettle herself and her family abroad when it's all over.

Soo-yeon makes a phone call to Ki-chul, claiming that she has found the money he requested and has information about the supervisor he may want to know.

Immediately after Sun-woo leaves, Mom and Dad follow in a rented car, using the tracker she put in his bag.

Sun-woo's team accompanies Soo-yeon to a cafe they have taken over, preparing the fake money she has to give to the man she is going to meet.

Soo-yeon walks out to the public street where she has been told to wait, while Sun-woo monitors all the cameras set up as well as the field agents they have placed near her.

Sun-woo runs through the crowd and toward Soo-yeon, stopping dead when he reaches her and sees the pained expression on her face.

Mom also starts searching the rented car for a planted bug, convinced that is how Ki-chul knew that they were trying to trick him, but nothing turns up.

Chief Song chuckles at that response knowingly, then looks down at the report listing Hedge Technet as the top candidate.

Using a wiretapping device she asked from her husband one night before, Mom searches the place top to bottom trying to find out a bug.

Even though Ki-chul is just a human-shaped shadow on the CCTV footage, Sun-woo thinks back the scarred man he met in China after the car accident.

Sun-woo meets the poor mother in the processing area, tells her that the daughter who saved the family and got them into this country is dead.

It is time for Yoon-jin to answer a scheduled call from her mother in the North but discovers that the secret phone is missing from her drawer.

Taking it from Ki-chul's hand, Yoon-jin answers and is utterly relieved to hear her mother's voice on the other end telling her that they arrived safely.

Sun-woo stays late at the office, where his facial identification software picks up on a possible match between Ki-chul and an old army photo.

Yoon-jin calls and Sun-woo leaves in a hurry without notice the program pick up on another match among the North Korean ranks, his Mom.

At home Mom and Dad test out the phone-hacking program, noticing that moving the phone interrupts the process.

He apologizes on Mom's behalf, takes her hand and promises to protect her, not caring whether his family understands or not anymore.

Inside Sun-woo's cubicle, the computer identifies two faces from the day Soo-yeon had died to two soldiers in the North Korean troops - Ki-chul and Mom.

Chief Song has Hyun-tae outfitted with bugs and earpieces so he can follow the orders he has to receive in Sun-woo's house.

Yoon-jin, who has contacted Sun-woo before for late because of work, is brought to the house by Ki-chul and his lackeys, and told to just do as she is ordered.

Sun-woo brings Yoon-jin in, Mom's expression is icy but forced as she plays nice in front of her son.

Sun-woo finds one of Mom's pills on the bathroom counter, but is stopped from investigating the medicine cabinet when his sister announces that the guests are leaving.

He sends through a bunch of code he managed to swipe before the second password was asked for, Chief Song underlines some numbers and draws a dollar sign next to them.

When Sun-woo is driving home from Yoon-jin's apartment, he recognizes a surveillance van with the license plate he caught on the day Soo-yeon died.