The Giver by Lois Lowry
The problem people usually have with The Giver is that it doesn’t really end. It just sort of… tapers off, irresolute. I know Lois Lowry wrote sequels, or "companions," but imagine being being alive and literate in 1993 and not knowing what happened to Jonas after he stole that baby and ran off into the wilderness. It wasn’t until the year 2000 that we got a sequel (of sorts) with Gathering Blue, and it wasn’t until Messenger in 2004 that we knew for sure what became of Jonas.