Soundless Prison
The castle has a number of dungeons somewhere in the lower sections of the castle. Here, Kairi and Pluto are imprisoned in one of the cells. Kairi is briefly visited by Saïx who explains to her that she will be the bait used to make Sora slay more Heartless in the plan to complete Kingdom Hearts. However, Naminé appears through a portal in the cell and helps Kairi and Pluto escape. Strangely, the bars of Kairi's cell were far enough apart that she could have easily escaped before being freed by Naminé. However, it could be possible that the Organization foresaw this and placed a barrier over the bars to prevent this.