A young girl named Rose finds herself in an old castle frozen in time and overwhelmed by vines and thorns. A mysterious rose is attached to her waist, capable of absorbing the color red and expelling it into the castle; by default, almost the entire castle is in greyscale, with only the red splashes from the rose and other objects resuming time or giving life to objects. Rose soon finds a giant creature. While initially afraid of the creature, she warms up to it when it goes out of its way to protect her. Forming a bond with each other, Rose and the Giant decide to travel through the castle, hoping to find out why she has this rose and answer the mysteries surrounding this castle. There is little dialogue in the game; almost all plot events are shown through vignette recaps and flashbacks, as well as reading journal entries.
Rose soon discovers that she is seemingly immortal; the power of the rose reconstitutes her no matter what happens to her body. Failure within a room simply restarts the room, and unlocking new areas of the castle sometimes requires gruesome self-sacrifices that only an immortal could unlock. The pair also finds another girl with a rose who looks suspiciously similar to Rose, Blanc, as a seeming antagonist.