a crumbling wall in Yucatan. Many people refer
to it as the Greek key."

Something began to glimmer in my mind--the vaguest, most tenuous
shadow of an idea; a tantalizing, hide-and-seek phantom of a
thought.

"_Turne Hellens Keye
Three Tennes and Three_,"

he quoted the doggerel verse.

We looked at him mutely.

"It is a tiresome truism," he went on, reflectively, "that what lies
close to the eye often escapes observation. For instance, these
windows have been staring at me daily, each with its nice little
eyebrow of design, and I overlooked the design until my subconscious
mind suggested to me that here, in all probability, lies Hellen's
Keye."

I remembered the entry in Freeman's diary, concerning the loss of a
"Keye," which hadn't been found among his father's papers, and of a
secret which had died with the older man.

"I think I told you," said The Author, "that this house was built by
master masons, shortly after the Grand Lodge was established in
London. Thirty-three is rather a significant number. Yet, how to
apply it," he paused, frowning.

"Without disturbing a Watcher in the Dark?" Alicia made light of
The Authors itch for mystery. "Aren't you rather forgetting the
Watcher in the Dark? Teller of tales, isn't it moon-stuff you're
trying to spin?"

"Who talks of a Watcher in the Dark?" asked a pleasant voice.
Accompanied by Mr. Johnson, Mr. Nicholas Jelnik had strolled up
unperceived.

"The Author," Alicia explained, mischievously, "is trying to make
sense out of nonsense."

"That," said Mr. Jelnik, smiling, "is not an uncommon occupation."

"It's all about a bit of doggerel we found on a scrap of paper in
the attic," I told him. And I quoted it, adding: "There was a column
of dots under it. The Author laments that he lost it, before he had
chance to unravel it."

"I lost it, walking in my sleep," said The Author, disagreeably.

"And now he's trying to make us believe that the design in the
brick-work above our windows, just because it's the Greek fret, is
Hellen's Keye," Alicia said, jestingly.

"Well, you know, if a thing means _anything_, it's got to mean
_something_," put in Mr. Johnson.

"Ain't it the truth, though?" hissed The Author, with fury.

Mr. Johnson was saved from stammering explanations by the irruption
of Beautiful Dog, who at sound of his voice had wriggled, and
cringed, and fawned his way out of the shrubbery, cocking a wary eye
to see that none of