In the film, the ogre's shape changing abilities and other magical powers are granted by a necklace which he must wear to survive during daylight. He offers the king unlimited gold, jewels and diamonds for his marrying the king's daughter, but the king refuses. When Puss in Boots tricks the ogre into morphing into a mouse, the ogre escapes him and realizes the trick, and then morphs into a large monster and attempts to kill him. But his necklace is stolen, and the princess, king, miller's son and cat are able to prevent him from catching the necklace by dawn.
In the film, the mice are on the side of the miller's son after an initial confrontation with Puss in Boots.