Deep in the forest, foxes live in an underground city built by the wolves they enslaved. Using the power of speech, they keep the wolves under their harsh rule. Wolves Isengrim, Hersent and their pups use secret passages to move between the animal and human worlds. When Isengrim is injured, a young boy named Silas comes to his aid. Silas finds speech difficult, but as his friendship with the wolves grows, he must fight to protect his new friends, and find his own voice.