Miles Morales comes across the long-dead Peter Parker. This Peter Parker is not from his world though; he's from somewhere else in the multiverse. With Parker's guidance, Miles will become Spider-Man: and through that he will become part of the ever-expanding 'Spider-Verse'.
In a world where there have been three Spider-Men in the past decade, not many people can say what the world needed was a fourth Spider-Man. Yet Sony have given fans just that, and then some, in the form of Spider-Man: Into the Spider Verse.