formed a combination dangerous to encounter and difficult to
circumvent.

There was a buzz of conversation up and down the hall as these two men
talked together in low tones. I knew now that I was face to face with
the most hazardous problem of my life.

I whispered to the auctioneer, who bent his head to listen. He knew
very well who I was, of course.

'You must not give up the necklace,' I began.

He shrugged his shoulders.

'I am under the orders of the official from the Ministry of the
Interior. You must speak to him.'

'I shall not fail to do so,' I replied. 'Nevertheless, do not give up
the box too readily.'

'I am helpless,' he protested with another shrug. 'I obey the orders
of the Government.'

Seeing it was useless to parley further with the auctioneer, I set my
wits to work to meet the new emergency. I felt convinced that the
cheque would prove to be genuine, and that the fraud, wherever it lay,
might not be disclosed in time to aid the authorities. My duty,
therefore, was to make sure we lost sight neither of the buyer nor the
thing bought. Of course I could not arrest the purchaser merely on
suspicion; besides, it would make the Government the laughing-stock of
the world if they sold a case of jewels and immediately placed the
buyer in custody when they themselves had handed over his goods to
him. Ridicule kills in France. A breath of laughter may blow a
Government out of existence in Paris much more effectually than will a
whiff of cannon smoke. My duty then was to give the Government full
warning, and never lose sight of my man until he was clear of France;
then my responsibility ended.

I took aside one of my own men in plain clothes and said to him,--

'You have seen the American who has bought the necklace?'

'Yes, sir.'

'Very well. Go outside quietly, and station yourself there. He is
likely to emerge presently with the jewels in his possession. You are
not to lose sight of either the man or the casket. I shall follow him
and be close behind him as he emerges, and you are to shadow us. If he
parts with the case you must be ready at a sign from me to follow
either the man or the jewels. Do you understand?' 'Yes, sir,' he
answered, and left the room.

It is ever the unforeseen that baffles us; it is easy to be wise after
the event. I should have sent two men, and I have often thought since
how admirable is the regulation of the Italian Government which sends
out its policemen in pai