Scene opens with a zoomed out shot of a cemetery, some how the statue of liberty in the background. Its raining, not hard but people have umbrellas. There's only a small crowd but they are close.
The camera zooms in to two males closest to each other.
Ray: I never thought Spengler would be the first to exit our mortal coil, leaving the physical realm like this just sucks.
Winston: Do you ever not make things scientific Ray?
Ray: it is unfortunately the curse of a broad mind Winston.
Winston Shakes his head but smiles at his old friend like he wouldn't have it any other way.
Winston: We had some good times, i'll miss him, if i didn't always understand him.
Ray: stop selling yourself short Zeddemore.
We see three more figures walk up to Ray and Winston from behind.
Dana: Hey guys you ok, i'm so sorry about Egon.
Ray is about to answer when out from behind Dana steps Peter.
Ray: Venkman!, I thought you couldn't make it?
Peter: Stantzy baby come on i wouldn't miss mr slinkies funeral now, no family here?
Ray: You know how disconnected their family was, didn't expect it to be honest
Peter: so how did it happen?
Ray: You know how the ghosts kind of dried up about twenty five years ago, full apparition dispersal, even the containment unit ghosts vanished!
Dana: isn't that dangerous Ray?
Ray: no no Dana they literally faded out from this existence with no major nodes left, like Vigo or the zuul
Dana shivers at the mention of Zuul. the big twenty something looking guys eyes suddenly light up.
Oscar: is that bad guy who took me?
Peter: Oscar you know your poor mother hates that, Sorry Ray inferior breeding.
Venkman pulls a cross eyed face pointing to the big guy. Ray laughs.
Ray: So yes he kept investigating their disappearance afraid it meant something, then some trans-dimensional portal he was working on backfired killing him
Dana winced at this while Peter frowns, the rain seems to let up and the priest runs from where he was waiting to start the sermon. both Janine and Louis stand the other side of the grave the offer a small wave.
The priest does the sermon.
Peter: oh here comes a nark
Peter points as some official type comes running towards them as Egon's funeral draws to a close.
Trebor: Good day, my name is Trebor, I represent everything Mr Spengler was in life.
Peter: we ain't paying nothing friend.
Trebor frowns and continues.
Trebor: No Mr Spengler gave me this book to give to a Mr Ray Stantz, The Funeral on the other hand was well compensated for.
Trebor hands a parcel to Ray and huffs off back towards a black car.
Ray: you do have a way with official people Peter
Peter: It's a gift, what you got there Ray?
They all watch as Peter snatches the parcel and unwraps a book, which he scrutinizes.
Peter: some book, it says about the existence of ghosts by some women Erin Gilbert and Abby Yates.
Winston: What does this have to with Egon?
They open the book and in Egons writing in the inside cover it says seek out these women, we will need them for the future. Peter and Dana Frown.
Dana: Me and Peter have get back for Sara, she's in her last year of school.
Oscar: Oh wow, I could stay with with the guys and help them mom, if they want?
Peter: Yeah you do that, it'll be good for you, the guys won't mind
Peter winks at the guys who just nod in confirmation.
Ray: Then it's settled we find this woman.
Fade to black
The same thing happens in the mansion with the tour, tour guide etc
Fade to black.
At the university where Erin Gilbert works, her book seems to magically reappear as she is seeking tenure in the university. Fed up of the ribbing she quits.
On her way out carrying her box of belongings Ray stantz pulls up in a dilapidated ecto 2.
Ray: hey young lady, i was wondering if you knew where I could find a metaphysical specialist by the name of Erin.
She looks at him doubtfully,
Erin: Why do you want to know who she is?
Ray: Oh i was wondering if she would like to talk to me about this book I found?
Erin rolls her eyes.
Erin: Someone else to laugh jokes at my old work, I get it ok ghosts don't exist!
Ray: Young lady i would assume by the defensive way you talk, you are indeed Dr Gilbert
Erin: Yes, yes i am
Ray: What if i was able to tell you ghosts did exist and me and a specialized team used to fight them a long time ago?
Erin: So the rumors are true, are you Dr Egon Spengler?
Ray: No i am an associate of his, Dr Ray Stantz, unfortunately Dr Spengler has passed on.
Erin: Oh!, Oh dear, he kept contacting me recently something about a psychomagnetherical disturbance of large proportions, I thought he was just another person who found my book and wanted to take the piss.
Ray: No Miss Erin I believe that Dr Spengler may have been on to something before he died and he believes you and maybe the other author of this book may be able to once again help save the great city that I like to call New York, and the world. Now let's go and find your colleague.
A slightly bewildered Erin puts her items in the car and enters herself, glancing to the back to see four dusty proton packs in a rack, her eyes widen as the familiar ecto 2 wail starts up.
Fade to black.
Ray meeting Abby and her associate Holtzmann, this scene right after the last, Jill dribbles over the old proton packs, since she's been working on similar stuff.
Unable to afford the rent on the old fire station, after selling his book store Ray rents a room above the same Chinese store. Give Oscar (who i haven't mentioned is still the exactly same Chris Hemsworth character Erin dribbles over)
So they are called to the mansion where they take then actual old proton packs and traps, Ray guaranteeing they will still work, ( half life of a thousand years etc) The encounter the ghost but the pke meter is giving strange signals like this ghost isn't made of the same stuff.
They get slimed, well Erin does, they try to bust the ghost the proton streams destroying shit like usual. but the beams don't seem to wrangling the ghost, even the trap seems to not work.
When Abby and Erin accidentally cross their streams the protonic reversal ( as explained by Ray that this ghost must have been forcibly summoned for the protonic reversal to send it back to where it came from instead, in a later scene)
Him and Holtzmann start work on a new reversed proton stream pack, as well as other reversed proton weapons.
Patty still joins the way she does, in fact have her as Zedemores niece or something too. The older ghostbusters now take a back seat as the rest of the movie pretty much plays out the same way, except we find out that Egon had found out that Rowan is using part of the building from the original film to power the machine that calls ghosts forth. (he also used to live in the building and was fed up of telling the story but no one believing him so he's used part of it to prove to everyone but it's taken him this long to figure out how)
So he killed Egon, linking him further into the film as a more fleshed out character too and all the more reason to bring his ass to justice.
As said the rest goes pretty much the same just with this new stuff woven in the mix, making an overall good sequel NOT a reboot, starring 4 women that now take over the title from the older guys who just work in the background.