Speaking of prologues, those poor inoffensive often maligned, numberless chapter before the chapter...
Recently I watched the movie Spotlight. If Spotlight was a novel it would have a prologue. The first four or five scenes take place in 1976 (25 years before the main focus of the movie begins.) The scenes take place in a police station. It's not quite clear what has happened but we know that a priest has been brought in for some kind of crime, and will not be held to answer for it.
The last of that prologue is the faceless priest, escorted by the assistant district attorney, being driven away from the station, free to go.
The next scene is at the Boston Globe and the main story begins.
The function of the prologue is important: it lets us the viewer know something that the characters in the movie do not: something is very wrong, it's been going on a long time, and the powers that be are covering it up.
The tension in Spotlight comes not from "did he do it" but "will they get away with it …again."
That's all possible because of the prologue. It's hard to hate something that plays such a pivotal role, no?
Well, that's the trick of course: pivotal role.
Unless a prologue IS pivotal to the manuscript, it's probably not useful and can be discarded. I often tell writers that if the backstory in a prologue is important, weave it into the narrative. In the case of Spotlight that would be impossible. No one involved in the coverup, nor any of the contemptible priests are going to be visiting with the staff of the Boston Globe to give them backstory. If anything quite the opposite.
You need to ask yourself: what's my story? Is it "did he do it" or "will he get away with it again." Knowing the kind of story you want to write, and the kind of tension you want to build will help you know if a prologue is the right tool to use.
And as an afterthought: you just gotta love a movie where one of the lines is "golfing is not a verb."