Cardiothoracic surgeon Oh Yeon Joo’s (Han Hyo-joo) father mysteriously goes 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 and 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. Yeon Joo later discovers that she can only leave the webtoon based on Kang Chul’s change in feelings. When that happens, the words ‘to be continued’ will appear and she will teleport back to the real world.