Seventeen-year-old Aya moves into an aging apartment complex with her father, only to discover that her younger sister sleepwalks every night, growing weaker as she unknowingly plays a deadly game of hopscotch. Following her sister’s footsteps, Aya begins seeing squares that shouldn’t exist and realizes the building’s corridors, stairwells, and rooms form a giant hopscotch board. The day they moved in, they had already stepped onto the first square. To save her family, Aya must find the impossible final square before the game consumes them.