There was a plan. A good plan. The Ghostbusters of Many Worlds would just split up and seek out the ghosts that had escaped from the containment unit in the dimensions those ghosts sought refuge in. Simple. Effective. And it should've gone off without a hitch... until something went wrong. It seemed small, but it hints at the chaotic presence of a being that Peter, Egon, Ray-and especially Winston-had hoped they'd never meet again. 2018'S Ghostbusters mega-event continues!.
