The Author opened his door just as we approached it, and held up an imperious finger.

“Did you hear it, too?” he whispered.  And walking ahead of us, he stole up the cork-screw stairway at the end of the side hall, lifted the latch of the attic door, and stepped inside.

It was frightfully dark up there.  If you peered through the uncurtained windows you could see tree-tops tossing like black waves against the dark sky, and in between them rolling clouds, and little bright patchwork spaces of stars.  And it was so quiet you could hear your heart beat, and your breathing seemed to rattle in your ears.  We strained our eyes, seeking to pierce the gloom, stealing forward step by step.  A board creaked, noisily; and then—­I could have sworn it—­then something seemed to move across one of the dormer windows.  It was so vague, so shadowy, that one could not distinguish its outline; one could only think that something moved.

The Author gave an exclamation and switched on his electric torch, trying to focus the circle of light upon that particular window.  There was nothing there.  Only, it seemed to me that something, incredibly swift and silent, flashed down one of the bewildering turns to which our attic is addicted.  But when we ran forward, the passage was empty.  We brought up at the red brick square of one of the chimney stacks.

Almost savagely The Author flashed his light over every inch of wall and floor.  Nothing.  But on the close and musty air stole, not a sound, but a scent.

The Author swung around and trotted back.  The window across which we thought we had seen something move was fastened from the inside, and there were one or two wooden boxes and a leather-covered trunk in the dormer recess.  He sniffed hound-like around these, and with an exclamation leaned over.  Behind the trunk crouched—­Potty Black, with a mouse clamped in her jaws.

“For heaven’s sake!” cried Alicia.  “The cat!  Sophy, what we heard was the cat!”

“Let us go,” said The Author.  And feeling rather silly, we trailed after him.

“You see,” said I, “there is nothing.  There never is anything.”

“Come in my room for a minute,” The Author whispered, and there was that in his voice which made us obey.

Inside his door, he opened his hand.  In his palm was a soiled and crumpled scrap of tough, parchment-like paper about the size of an ordinary playing-card, so frayed and creased that one had difficulty in deciphering the writing on it.  There clung to it a faint and unforgetable scent.

“It was behind the trunk, partly under the cat’s black paw.  I smelled it when I leaned over, and I thought we might as well have a look at it.” said The Author.

And on the following page is what The Author had found.

’"Shades of E.A.  Poe, and Robert Louis the Beloved!  What have we here?” cried The Author, joyously, and stood on one leg like a stork.  “Was there a Hynds woman named Helen?  ’Turn Hellen’s Key three tens and three?’ Some keyhole!  I say, Miss Smith, let me keep this for a while, will you?”