Beauty's new master lives in Bath and has bought a horse on the advice of his doctor. He doesn't know anything about horses, so he hires a man named Filcher as a groom. (Know what "filching" means? There's a pretty clear clue about this dude's character tucked inside his name…)
This new master orders lots of good food, but is totally out to lunch when it comes to his new groom. Although at first everything's fine—the groom "kept the stable clean and airy […] groomed me thoroughly and was never otherwise than gentle" (30.2)—after a while Beauty thinks his food is coming up short. However, being a horse, Beauty can't say a word about this, and instead "I wondered why my master did not see that something was the matter" (30.2).
One day when Beauty is out with his new master, a helpful passing gentlemen (we've seen a lot of those, haven't we?) stops them to remark on how unhealthy Beauty looks. He tells Beauty's master to look into the situation and check out things in the stable.
Beauty relates his frustration at watching the groom and a little boy steal (or, you know, filch) the oats from his supply—he knows what's been going on. At last a policeman comes and apprehends both groom and boy; the boy's set free, but the groom serves two months in prison.