Mark is a single father struggling to raise his five year old boy with a fairly normal life. He takes him to his family's beach house for the summer to hopefully lift his spirits and have some fun. Haechan is fresh out of college, ready to start his career as a veterinarian. His summer plans are made for him as a gift from his best friend Chenle, his beach house all to himself and of course his dog sunny. With a chance meeting of temporary neighbors the summer takes a turn that neither had expected.

It was all Dongsookie at first, Until Donghyuck had to pretend he was his sister. And keep up the promise, "I wont fall in love with your boyfriend" starts getting harder. Mark was such a gentlemen. And Dongsookie was pregnant.