From the back cover:

"Halloween Night - when ghosts and spirits walk the earth in search of a Really Good Time. It's usually a busy night for the Ghostbusters as they get to deal with all kinds of paranormal peturbances. But this year... things are going to be different.

Now an ancient horror is rising from an unsuspecting pumpkin patch with one goal in mind - perpetual Halloween, the holiday that lasts forever! You know who to call!"