If this was just a story about a normal girl going to prom and having a good time, it wouldn't be on this website. You know trouble is coming. Let's recap, though. Clare had bought a dress that fits in with the dress code.
She checked it at the store. When she realized the heels might cause a problem, she double-checked it, and it was still OK. As far as she was concerned, there shouldn't have been a problem with strolling right into prom.