In 1998, Tony Healy and my friend, Paul Cropper descended on the small Northern Territory town of Humpty Doo to investigate a poltergeist infested house. They didn't have long to wait. While Paul was talking to two of the occupants, there came a clatter, like hail on the corrugated iron roof and, as he looked upwards, a dozen grey pebbles fell to the floor from the ceiling. As it turned out, this was not to be an isolated experience for them. Trickery, they soon discovered, was out of the question. However, it was pretty easy to deduce that the pebbles came from the driveway outside but how did they get to the ceiling? No-one ever saw them move from the driveway into the house, or onto the roof, or even hover below the ceiling. Paul got the impression that they had simply passed through both the roof and ceiling without leaving any holes. It is not clear from their reports whether the clatter was heard on each occasion, so did they simply materialise under the ceiling? And why, when the ground was saturated outside, did they remain dry, if not warm? And this phenomenon is not limited to Humpty Doo. Harry Price, the psychic researcher, said that he had heard of many objects falling from ceilings, but never anyone ever seeing anything go up to the ceiling.