Arnold, an unemployed middle-aged mouse, confides to his wife Maria that he suspects his entire world is nothing more than a set, and his life a scripted performance. When his best friend Ramiro dies under mysterious circumstances, he traces the conspiracy to a monolithic corporation whose influence reaches every corner of their daily lives.

Mugaldekoak is set in the early 40s, when, on this side of the border, the wounds of the Civil War were still open and, on the other, they were living under occupation by the German Army. The tale revolves around the Comète Network, an initiative developed during World War II on the border with Navarre: the clandestine evacuation of British pilots brought down in enemy territory.