Reply To: ITT we explain to each other song lyrics
But “Chapter 2: In which…” makes sense only because the thing in which Bob is learning his salad-consumption technique is stated, i.e. the chapter. Plus, titles of any medium may be imperfect grammar, many are just the name of an object or person.
A sentence, standing on its own, such as “In which Mary goes to the zoo” lacks context, and I would argue is a sentence fragment.