Code of the Clans is a field guide in the Warriors novel series.

Code of the Clans is about the warrior code that guides the Clans in their everyday behavior and decisions.

In the introduction, the book summarizes how the Clans were formed.

The next chapters feature Leafpool explaining the Warrior Code to the reader, through the point of view of curious loners visiting the Clans.

She explains failed additions to the Code in the final chapter.