"Good," said the Assistant Commissioner, nodding his approval. "You
will have to check 'phone messages in that way until you have run your
mimic to earth, Inspector. I don't believe for a moment that it was
Sergeant Sowerby who rang you up at Dr. Stuart's."

"Neither do I," said Dunbar grimly. "But I begin to have a glimmer of
a notion who it was. I'll be saying good-night, sir. Dr. Stuart seems
to have something very important to tell me."

As a mere matter of form he waited for the report of the constable who
had gone in quest of Sowerby, but it merely confirmed the fact that
Sowerby had left Scotland Yard over three hours earlier. Dunbar
summoned a taxicab and proceeded to the house of Dr. Stuart.



CHAPTER VII

CONTENTS OF THE SEALED ENVELOPE


Stuart personally admitted Dunbar, and once more the Inspector found
himself in the armchair in the study. The fire was almost out and the
room seemed to be chilly. Stuart was labouring under the influence of
suppressed excitement and was pacing restlessly up and down the floor.

"Inspector," he began, "I find it difficult to tell you the facts which
have recently come to my knowledge bearing upon this most mysterious
'Scorpion' case. I clearly perceive, now, that without being aware of