After being left to raise seven children alone, Bang Chan does everything he can to keep his family together. But with their dad constantly working, seventeen-year-old Lee Know has quietly become the second parent-taking care of Changbin, Hyunjin, Han, Felix, Jeongin, and especially their youngest, Seungmin. Lee Know loves his siblings, but he's exhausted from carrying responsibilities that were never supposed to be his. When a small argument with Seungmin finally exposes just how overwhelmed he is, years of buried emotions begin to surface. As the family confronts how much they've all been struggling, they have to learn that being a family doesn't mean one person has to carry everyone alone.