Wailing banshees are not the only mystery at Banshee Towers—it hides other secrets too! Does the turnstile man or the owner know anything about them? Buster and Bingo—as well as the Five Find-Outers—are hot on the trail.
The mystery itself concerns an old building on top of a hill, an art gallery where a banshee wails every Thursday and drives out what few punters they have. The banshee, Fatty assures everyone from the start, is a fake—a clever device set up to make it seem like the place is still haunted, as it used to be a hundred years ago. So it's sort of like Scooby Doo, where the gang figures out the ghost is actually a mechanical contraption, and the baddies would have got away with it, too, if it wasn't for those pesky kids. In this case, the baddies are smuggling valuable paintings out of the building and selling them in America. Apparently all the paintings are lent by a rich guy in Austria—and while on display at the Banshee Towers gallery, a French artist sits there and copies them. The owner of the gallery, Mr Engler, is in cahoots with the artist as well as the turnstile man, and together the three of them have a racket going. The paintings are smuggled out in lead pipes, which are stacked up outside as if work is being done to the plumbing.