Cardiothoracic surgeon Oh Yeon-joo's (Han Hyo-joo) father mysteriously went missing while writing the last chapter of his webtoon "W". Yeon-joo goes to his office and is shocked to see a scene of the dying Kang Chul (Lee Jong-suk), the main character of W, on her father's computer. While reading a note left behind by her father, a hand from the monitor pulled her in. She finds herself on the rooftop of a building next to a bleeding man. She manages to save him and realizes that the person she saved was Kang Chul. One of the witnesses ask her to remain in the area to provide testimony but she is suddenly transported back into the real world, more specifically, to her father's office (Kim Eui Seung who plays as Oh Seong Moo), where only a few minutes had passed. Because of her sudden disappearance, the witness, accompanied by the police, then suspect her as the suspect, concluding that she left the scene of the crime without due testimony.