Ray, Egon, and Winston (Venkman married Dana Barrett and raised Oscar) are still ghostbusting. A particle accelerator at Colombia University led by a team of new professors (Vince Vaughn and Jack Black) accidentally opens a portal to another dimension, and spectral beings begin crossing over into NYC and causing chaos.
Of course, the old team starts combating these new ghosts, but at one point, they get their butts handed to them. Obviously they make contact with Vaughn (the new Venkman character) and Jack Black (the new Ray character). Vaughn and Black realize it's their fault for this new outbreak of ghosts, so they offer to become Ghostbusters themselves.
Everyone agrees, and they build a new team: Dave Chappelle and Will Ferrell are hired on. Tully (Rick Moranis) has retired, and their new lawyer is Rainn Wilson.
Egon busts out some new experimental equipment: new Proton Packs, more sleek and high-tech, and a new Ecto-1, with updated features and gadgets and such (like an iPod?).
The new team goes about trying to right their wrong by busting the ghosts they helped release, and do a pretty good job at it. But then the Mega Monster Ghost Leader bursts through the portal and captures the new team.
The old Ghostbusters (Ray, Egon, and Winston) gets wind of this. So, they bust out the old-school Proton Packs, break out the original Ecto-1, and go rescue the new team. The rescue is successful, and both teams unite to take out the Big Bad Guy over New York City in the climactic finale.
In the very end, Venkman, Dana, and an adult Oscar get out of a cab in the middle of downtown chaos, meet up with the Ghostbusters, new and old, share a hug and such...
THE END
Bobby Brown would, of course, HAVE to be part of the soundtrack.
