What purpose does the prologue serve?

The prologue reflects the setting and shows where the story is heading.

Explanation:

A prologue is an introductory section to a literary work. Its purpose is to introduce themes and characters that will appear later in the main body of the text and to provide necessary background material for understanding the story ... The prologue is an extension of the narrative that follows, written in the same narrative voice. It reflects on events, setting, and characters in the novel.