The Island Keep is an Enforcer stronghold in Sambria. It consists of the main fortress complex, several towers, and a dungeon below.

In Time Jumpers, Owandell imprisoned Stafford, Harmony, Destiny, and Honor in the fortress after kidnapping them. They were imprisoned on the top floor of the 2nd highest tower, which was partially shielded from Wayminders. There were a lot of guards at the base of the tower and in a guardsroom halfway up. Violet discovered all of this when spying on the fortress after Governor Vass told her and Cole that the royal family was located there. Eventually, she opened a wayport to the top floor, They emerged in a semicircular room with iron shutters masking the windows. Honor and Harmony sat at a table, while Stafford and Destiny were resting on two of four narrow beds. All but Stafford managed to escape the stronghold.