This post over at io9 had me musing on how I would do a third Ghostbusters film, amongst other films.
So, it I were writing Ghostbusters III, I'd spend a big chunk of the first act setting up that Venkman has developed a pretty happy life with Dana and is a great dad for Dana's son, Oscar.
Then I'd hit him with a bus. Murray doesn't want a big part, so let's just kill him early and get him out of the way.
Filling the void in the team is Oscar. Oscar hero-worships Venkman and has joined the Ghostbusters. I'd cast someone like Clark Duke in the role. He looks like an Oscar. Despite his hero-worship, Oscar is frequently the opposite of Venkman. He doesn't have a natural manner with women. He doesn't stroll through life. But he is actually a much better and much more dedicated scientist.
The central, paranormal conflict of the story is driven by the containment unit. Spengler and Stanz observe that it is becoming unstable; ghosts are escaping and weird violations of natural law are occurring. This necessitates entering the containment unit somehow.
I have no idea what techno-babble has been offered for how the Ghostbuster's containment device works. But I sorted of liked an idea offered in Dan Ackroyd's Ghostbusters 3: Hellbent script, where the Ghostbusters visit hell, but it's an alternate dimension version of Manhattan. I'd offer that the containment unit actually creates a pocket dimension which is a mirror of New York City, but only inhabited by captured ghosts (and with an increased flow of time).
The Big Bads are a group of captured ghost who have taken advantage of being cooped up for millennia with these other ghosts and all their occult knowledge. They've learned secrets from them and stolen powers. Now they want out and might just have the power to do it.
Or at least enough power to trick Spengler and Stantz into going into the containment unit (somehow), which allows the Big Bads to escape and trap them therein. And an army of ghosts from 30 years of ghost-busting follow them out.
Now we get to the Underwear Gnome part of my idea. I.e., I have no middle part. But the big reveal is that one of the Big Bads is Venkman himself, who provided the smarts of the trio. He didn't die when the bus hit him, but was knocked into a coma and had an out-of-body experience. Then his AWOL spirit got 'busted and tossed into the containment unit. When he escapes he makes a beeline for the hospital, chased by Oscar and a team of younger Ghostbusters. When they fail to contain him, he re-enters his body and wakes up to find Dana reading to his formerly comatose body.
Meanwhile, Stantz and Spengler have been locked in the containment unit for what seems like two years to them (and a few hours to us). In between fighting off the remaining ghosts, they have built an inverted containment unit, giving them a portal back to the living world. When they crawl through it they come out someone's microwave in the middle of the night and get chased out of an apartment.
After that, they re-unite with Venkman and Winston Zeddmore (who has been leading the fight against rampaging ghosts; I'd like to imagine he leads the day to day business of Ghostbusters, because Spengler and Stantz would suck at that). Then they, along with Oscar (and whatever other young, edgy Ghostbusters have been added) defeat the two remaining two Big Bads. Alternatively, Venkman could just inspire Oscar and then stay in bed, recuperating.
That's the bounds of my idea. I don't even have a good idea for who the two Big Bads are. Maybe they're Bonnie and Clyde (but how did they haunt their way to NYC), maybe it's Dutch Schultz and Sid Vicious. An oddball pair might be more fun.
And that's what I think of when I walk home from work. Or in the bathroom. Of course, no matter what, a third Ghostbusters would probably Suck. Might as well have crystal skulls involved.