The Tree of Life is dying, and with it dies the planet Mama, as well as its inhabitants. Sehun takes it upon himself to leave the planet to search for something to cure the tree of its illness and restore life to their home planet. However, his lover, Luhan must stay behind, because he was born with a heart too weary for space travel. Just the force of taking off in the ship would cause his heart to burst, so he is doomed to be forever stranded on the planet Mama. That is why Sehun wants to still save it. He must do so for his lover, even if that means they must be apart for a long who knows how many years.