The Island of Mystery is a fictional island that only exists in these books. It is in the shape of a capital I and M joined together. In between the I and the M, there is a tiny o, and that is where the Community Centre is. The Community Centre is where all of the spies find out what missions they've been assigned to, and where they all live.

To tourists, the I, M shaped island stands for Island of Magic, the tourists and people who live there only have the I, they have no access to the o or the M. To the spies, It stands for Island of Mystery, but the M can also make it Island of Missions.