When Franco, a teenager living in the monastery at Monte Cassino in 1944 uncovers a long-lost Roman Eagle, the fabled Aquila for the Jupiter Legion, he sets in motion a desperate struggle to prevent the Nazis from using it to win the war. In a do-or-die mission, Franco and Dulcie, a teenage mountain girl, must steal the Eagle back and escape before its deadly power is unleashed. Pursued by the implacable forces of the SS they will discover not just the secrets of the Eagle but also themselves.