"They all took place about the time the moon was at the full. There
were twenty-eight in all." Malcolm Sage felt in his pocket and drew
out a paper. "These are the figures."

In his eagerness Sir John snatched the paper from his hand, and with
Inspector Wensdale looking over his shoulder, read:

Day before full moon . . . . 4
Full moon . . . . . . 15
Day after . . . . . . 7
Second day after . . . . . 2
--
Total 28 . . . . . . 28

"Well, I'm damned!" exclaimed Sir John, looking up from the paper at
Malcolm Sage, as if he had solved the riddle of the universe.

The inspector's only comment was a quick indrawing of breath.

Sir John continued to stare at Malcolm Sage, the paper still held in
his hand.

"That made matters comparatively easy," continued Malcolm Sage. "The
outrages were clearly not acts of revenge upon any particular
person; for they involved nine different owners. They were obviously
the work of someone subject to a mania, or obsession, which gripped
him when the moon was at the full."

"But how did you fix the actual spot?" burst out Inspector Wensdale
excitedly.

"Each of the previous acts had been either in a diametrically
opposite direction from that immediately preceding it, or
practically on the same spot. For instance, the first three were
north, east, and south of Hempdon, in the order named. Then the
cunning of the perpetrator prompted him to commit a fourth, not to
the west; but to the south, within a few yards of the previous act.
The criminal argued, probably subconsciously, that he would be
expected to complete the square."

"But what made you fix on Hempdon as the headquarters of the
blackguard?" enquired Sir John.

"That was easy," remarked Malcolm Sage, polishing the thumb-nail of
his left hand upon the palm of his right.

"Easy!" The exclamation burst involuntarily from the inspector.

"You supplied me with a large scale-map showing the exact spot where
each of the previous maimings had taken place. I drew a square to
embrace the whole. Lines drawn diagonally from corner to corner gave
me the centre of gravity."

"But----" began the inspector.

Ignoring the interruption Malcolm Sage continued.

"A man committing a series of crimes from a given spot was bound to
spread his operations over a fairly wide area in order to minimise
the chance of discove