Kwon Dohoon is an affectionate husband and father, but he is always late or absent at every family event because of his overwhelming work. After putting up for ten years, Kang Yura finally loses her temper and invites Dohoon's ruthless supervisor, Chief Oh Cheonryeon, to their home.

Even after meeting Chief Oh, Yura can hardly discard her suspicions. Meanwhile, Dohoon prepares an event at a luxury hotel for his wife.

Yura and Chief Oh encounter again at the hotel suite Dohoon booked. Dohoon attends his daughter's school play and meets his friend, Thomas Wolfe.

Dohoon learns the truth while searching for the sniper who injured his colleague during a mission. Wolfe becomes the target of another sniper.

Chief Oh notices the gunshot wound on Wolfe and recalls someone. Yura gets a call and hears a voice she had long forgotten.

Dohoon is troubled after getting unexpected information about Chief Oh. Yura comes face-to-face with the mysterious caller.

Jo Taegoo knows about Yura's past, and his subtle threats make her anxious. Dohoon and Chief Oh try to read each other while hiding their true intentions.

Taegoo consents to leave Korea on one condition. Dohoon finds a picture while tracking down Chief Oh and gets assigned to a sniping mission.

The NIS senior/director calls Dohoon and asks if he found the sniper that killed Butterfly and where that bullet hit her. Director expresses his suspicions about Chief Oh being involved in Butterfly’s murder, while at the NIS headquarters, Ma Youngji tells Chief Oh about Butterfly’s situation and mentions Dohoon was the only agent who was there when Butterfly was killed. It turns out Chief Oh didn’t know Dohoon was the one sent to kill Butterfly.

The childhood history of Yura and Taegoo.

The story when Dohoon first met Yura.