The male protagonist's family went out to play, and his son and daughter were playing hide and seek and disappeared.In the forest, the male protagonist, who was looking for his child, saw his daughter covered in blood and his son who fell off a cliff.The police gave the male protagonist, who was holding his son's shoes and crying bitterly, the buried handkerchief (the handkerchief used by children to cover their eyes while playing hide-and-seek).

The male protagonist doubted his daughter and questioned her, causing her daughter to be hurt.The hero's wife was very angry and divorced the hero.

The hero's daughter called her grandma, and the hero asked her daughter's purpose and where she went.The daughter avoided answering where she had gone.

The male protagonist hurried back to the police station to attend the meeting.The male protagonist saw the video of the car rental suspect and thought it was his daughter.Moreover, the phone number of the male protagonist’s daughter was included in the list produced by the cell phone towers around the crime scene.

The male protagonist looked at the red fiber evidence he found, ran home, and looked through his daughter's room.The male protagonist's daughter's door was marked, and there were two marks. The male protagonist only saw one, and the daughter knew that someone had entered her room.The male protagonist suddenly sees the red pendant on his daughter's schoolbag and breaks the cup.

The police found a video of the girl who rented a car. She was not the hero's daughter, but Song Min Ah, one of the two girls (Song Min Ah and Park Ji Yeon) who stole mobile phones on the subway.

The male protagonist recognized Song Minya, but did not tell anyone at the police station and secretly investigated on his own.The male protagonist found Song Minya's social account and made an appointment with Song Minya, but it was Park Ji-yeon and a man who came. The male protagonist did not show up, followed Park Ji-yeon, was discovered, and disappeared.

The male protagonist went home and questioned his daughter. The daughter cried and asked him to believe her, but then turned around and changed her face.The grandmother also made the male protagonist believe in her child.

The police arrested the man who was with Park Ji-yeon, Choi Young-min.Li Yuzhen and Gu Dahong analyzed the case and felt that the scene was very contradictory and Cui Yingmin might be an accomplice.

Li Yuzhen and the male protagonist went to inquire about Cui Yingmin's landlord. The landlord was injured and lied that it was him who hit him, but the male protagonist saw it out.The male protagonist was following Park Ji-yeon that day and was seen by the landlord.

Goo Dahong found out that Song Minya bought medicine to treat diabetes to lose weight. The medicine was also found in the blood of the victim. The victim was probably Song Minya.

The police originally arrested Song Min Ah, but instead arrested Park Ji Yeon.Park Ji-yeon used Song Min-ah's card. After Park Ji-yeon saw the male protagonist, she told him to let her go, otherwise she would tell him that Song Min-ah went to see his daughter.

Police now suspect Choi Young-min and Park Ji-yeon of killing Song Min-ah.But there was no evidence, and Cui Yingmin's mouth was difficult to pry open, so he had to let Cui Yingmin go first and then follow up and monitor him.Li Yuzhen and Gu Dahong investigated the case between Song Minya and the hero's daughter. Gu Dahong discovered that the hero was secretly investigating and hid the matter from Li Yuzhen.

Park Ji-yeon was released and told the male protagonist that the last time she saw Song Minya was on the 11th. Song Minya went to see the male protagonist's daughter because the male protagonist's daughter stole Song Minya's mobile phone.

The hero's daughter came to the police station to give him clothes, and when she got home she burned the red pendant.When the male protagonist came home and saw that the pendant on his daughter's schoolbag was gone, he asked his daughter if she killed Song Minya.The daughter asked the hero if he doubted the death of his brother and mother.At this time, Team Leader Wu came to the door with his team members!