In a recently reunified Korea, robots have integrated seamlessly into society. They are our teachers, our bus drivers and policemen. They are our lovers. They are even our children.

Eleven-year-old Ruijie sifts through scrap metal in a Seoul junkyard, searching for anything that might repair her failing body. There amongst the piles of junk she happens across a robot boy: lifelike, strange and unlike anything she's seen before.

Across the city, estranged siblings Jun and Morgan Cho haven't spoken since the abrupt disappearance of their robot brother Yoyo, which shattered their childhoods and left a gaping hole in their lives. But Ruijie's discovery is about to bring the lives of brother and sister hurtling back together, forcing them to confront the reality of Yoyo's true nature, and the dark purpose their father never revealed.