How they look
who their freinds are
how much money they have
Denotation is my best answer, sorry if its wrong.
If the "books" wasn't a plural, it would be "his" but since it isn't singular, it would be "their"
As the title suggests, a treasure, but more specifically alluded in the plot, it's the pirates'treasure . However, a treasure is always the symbol to depict the immorality of that age when Stevenson wrote this novel of adventures.
