The bathroom! Why hasn’t she thought about it in the first place? That sounds like the perfect place to hide where his father won’t find her before he could unceremoniously throw her out of the tower. Plus it being accessible by a hidden bookcase door is an amazing bonus too. Now she needs to get inside so she won’t be found out.

“Yes that is a great idea, young man! I shall get inside the bathroom right now and thanks!”

She wastes no time getting inside the bathroom. Sure it is chilly, medieval, and small but that would do for a hiding spot so Isa is not complaining about it.