"Suddenly, all the doubts I haboured for this strange human world, after I woke up from this long sleep, vanished. Just like that, it was all gone. All the fears, anxious heart pounding because of undiscovered reasons - all gone. Strange. Being in the arms of this human boy, made me feel...... safe. As if my heart recognised him." - Angel, Kim Seol-hyun 

When a fallen angel accidentally saves a 10th grade boy from his death, she changes into human and eventually falls for him. She was told that her being human, was fated, as there was a purpose for her to be fated to be human one day. However, the boy, Nam Woo-hyun, does not return love to her as he did not want to hurt his friend, Lee Sung-yeol, who was already in love with the angel. Hurt, the angel decides to end her life instead of living as human, remembering her first heartbreak forever. This does not work and she wakes up, with all memories of her life as human, erased cleanly from everyone's mind, including herself. But what happens when she once again encounters the same boy and starts feeling a pounding anxious heart in this "stranger's" embrace. Also, still in search of her purpose and reason for being fated to be a fallen angel, a human. 

After all, even angels can't escape from destiny and love.