Role in the film
He was first seen when the Pevensies and the beavers escaped from Maugrim and his wolf police. The wolves caught up to the fox, demanding him for answers about the children. The Fox saved the children by lying to Maugrim, telling him that the Humans headed north, and so he ordered his wolves to smell them out before they took off, sparing the Fox.
He was threw across the snow causing him to "yelp", as the wolves ran off. Later, Fox, the beavers, and the children talked about the war with Jadis the White Witch, while his leg is get healed by Mrs. Beaver and he left.
Later on, Maugrim and his wolves tracked down Mr. Fox and delivered him to the Witch, declaring Fox as a "traitor", rallying the Fox in the Shuddering Woods. And there he apologized to Edmund by calling him "Your Majesty" but the Witch believed he was talking to her and told him to not waste his time flattering her and the Fox clarified to her that he was talking to Edmund, angering the Witch to the point that she was about to turn him into stone with her wand, before Edmund, in an attempt to save the Fox, stopped her by revealing that Aslan was gathering troops near the Stone Table, to which the Fox shaked his head in disappointment, knowing that the Witch is not to be trusted and turned to be right when The Witch told Edmund that it was good that the traitor knwe honesty before die and proceeded to turn the Fox into stone to Edmund's horror and commanded the Wolves to gather the faithful, that if it was a war Aslan wanted, it was a war he would get, demonstrating by casually turning a butterfly to stone as well. The Fox is later seen at the castle of Cair Paravel in the coronation of the Pevensie siblings, believed to be "unstoned" by Aslan.