A headless horseman. A haunted brewery. The complicated nature of temporal mechanics across the dimensions. The Ghostbusters can handle all of that, no sweat. But a sinister force is on the horizon, one they barely survived before, and at a great personal sacrifice. Tiamat made a deal to leave the Ghostbusters' earth... but what's the fun of being a god of chaos if you can't find a few loopholes? Mass Hysteria is in full effect as CROSSING OVER continues!