Fav of min often have no or minimal plot like Answer Me 1997 , and if there is, most of then are simple to figure out like Another star, Healer, etc.
I'm the kind who thrives on spoilers, but the reason I still watch the show is because I feel the need to see for myself their deadpan bickering, those beautifully melancholic expressions, those wtf-just-happened bewilderments, and Eun Tak's sunshiney smiles.
He seem to know who she is.