poison; and although I should have come to see you in
any event, because you have helped me more than once, I came to-night
at the suggestion of the Commissioner. He instructed me to retain
your services if they were available."

"I am honoured," replied Stuart. "But after all, Inspector, I am
merely an ordinary suburban practitioner. My reputation has yet to
be made. What's the matter with Halesowen of Upper Wimpole Street?
He's the big man."

"And if Sir Frank Narcombe was really poisoned--as Paris seems to
think he was--he's also a big fool." retorted Dunbar bluntly. "He
agreed that death was due to heart trouble."

"I know he did; unsuspected ulcerative endocarditis. Perhaps he was
right."

"If he was right," said Dunbar, taking up the piece of gold from the
table, "what was Gaston Max doing with this thing in his possession?"

"There may be no earthly connection between Max's inquiries and the
death of Sir Frank."

"On the other hand--there may! Leaving Dr. Halesowen out of the
question, are you open to act as expert adviser in this case?"

"Certainly; delighted."

"Your fee is your own affair, doctor. I will communicate with you
later, if you wish, or call again in the morning."

Dunbar wrapped up the scorpion's tail in the piece of tissue paper
and was about to replace it in his note-case. Then:

"I'll leave this with you, doctor," he said. "I know it will be safe
enough, and you might like to examine it at greater leisure."

"Very well," replied Stuart. "Some of the engraving is very minute.
I will have a look at it through a glass later."

He took the fragment from Dunbar, who had again unwrapped it, and,
opening a drawer of the writing-table in which he kept his cheque-book
and some few other personal valuables, he placed the curious piece of
gold-work within and relocked the drawer.

"I will walk as far as the cab-rank with you," he said, finding
himself to be possessed of a spirit of unrest. Whereupon the two went
out of the room, Stuart extinguishing the lamps as he came to the
door.

They had not left the study for more than two minutes ere a car drew
up outside the house, and Mrs. M'Gregor ushered a lady into the room
but lately quitted by Stuart and Dunbar, turning up the lights as she
entered.

"The doctor has gone out but just now, Miss Dorian," she said stiffly.
"I am sorry that ye are so unfortunate in your veesits. But I know
he'll be no more than a few minutes."

The girl add