Sherman Holmes, the eccentric, easily spooked detective, and his practical partner, John H. Garden (with his secret alter ego, Joanne), find themselves facing their most terrifying case yet. Despite Holmes's fervent dislike for all things Halloween , they are hired by a mysterious client, Mr. Harry Twister, to spend the night of October 31st in a notoriously haunted house.

Initially dismissing the tales of spirits as old wives' tales, their skepticism quickly evaporates. From phantom footsteps and slamming doors , to an evil cackle, ghastly faces at windows, and the appearance of a ghostly Victorian lady, Holmes and Garden are pushed to their limits, their courage tested by what seems to be genuine paranormal activity. Armed with a baseball bat , an antique cassette recorder , and Garden's ever-present toilet roll, they document their terrifying ordeal.

But when they report their findings to the ever-skeptical DI Streeter, the "haunting" takes an even more shocking turn. What if the ghouls, groans, and ghostly apparitions were all part of an elaborate trick? Can Holmes and Garden recover from being the butt of the ultimate practical joke, or will this elaborate deception spark a new kind of "war" between the bumbling detectives and the local police?