Construction workers have inadvertantly released Achira, a ghost that can spread disease. The only ones who could stop this ghost are the Ghostbusters, but they have long since disbanded. In fact, only Egon is still in New York City. He is now teaching a college class, but his four students may prove very helpful against this nasty ghost.
A Demon seed inhabits a Professor's plant, and takes over the building. The plant is destroyed, and the demon takes on another plant, in the park. Kylie thinks this demon is a helpful Amazon Plant, however she is wrong. It's really a civilization destroying demon inhabiting a seed. Can the EGB's stop Kylie before she has a chance to freeze it and send it back to the Amazon?
Slimer gets trapped in the containment unit (and Peter Venkman isn't even here to see it), surrounded by some very vindictive ghosts that remember him, including a demon named Surt who wants to bring about Ragnarok. Eduardo goes in to save Slimer, while the rest of the EGB has to bust a demon hound in the Firehouse.
Recent thefts of crystal skulls bring Egon Spengler into contact with an old associate, Dr. Edward Carrillion, who owns one of the skulls. But it turns out Carrillion is controlling the ghosts stealing the skulls, in hopes of completing the set and opening a dimensional gate, from which will pour a horde of ghosts under Carrillion's control. Instead, Carrillion falls into the dimension and faces eternal torment.
The long awaited return of the ENTIRE Original Ghostbuster cast. Janine invites Peter, Ray, and Winston back to help celebrate Egons birthday. However, there's a little friction between the new team and the old team, when the RGB's decide to take over the buisness again like nothing happend. As they go out on their first case in years, the EGB's take some time off. Janine is worried about the EGB's and there failing self esteme, and she corners Egon about it. However, they go out on another call. A Ghost ""Clone"" is attacking a nearby bridge, chewing on the steal cables. The RGB's figure that if they trap these 4 ghosts, they'll soon be dealing with 8. So, they stall them by throwing them nearbye car parts, so the people on the bridge can be given time to get off. But, the bridge starts to fall....and here come the EGB's to the rescue with a change off heart. They rescue the RGB's, and trap the ghosts, before they could be told not to...So, the RGB's and EGB's discuss there next move. T
Peter's vaction in Hudson Bay is rudely interrupted when a new ghost emerges in the waters of the city, that's at least 2 miles wide, and 4 miles across. The EGBs and RGBs find out that it's a sort of, baby Bermuda Triangle. They try two times to stop it with all their proton energy combined. They manage to drive it back and weaken it, but they do little in the way of stopping it. As it starts to invade the city, and even manages to devour the Twin Towers, Roland reveals the Ecto 3 and 4. A giant truck with an extra large Proton Gun on top, and a garbage truck transfered into a trap. They ""corner "" the entity, and manage to stop it once and for all, and both the Extreme Ghostbusters and the Real Ghostbusters have Thanksgiving dinner together.