Harry considered it safest to keep apart from his partner in public, and for that reason failed to speak to him.

When he afterward learned which room Old King Brady occupied, he quietly went up there and was admitted.

In whispers they explained to each other all that transpired and the old detective was delighted over the boy’s success.

“So the mysterious woman in black was the girl smuggler, eh?” asked the old detective.  “Well, I’m surprised.”

“Her warning you, shows that she has some regard for us and don’t wish to see us come to grief,” replied Harry, sentimentally.

“On the other hand, it may have been a diplomatic move on her part to bluff us off until they smuggle that big consignment of diamonds over the border,” replied Old King Brady, practically.

“Well, she didn’t succeed.”

“By no means.”

“Have you formed any plan of action?”

“Only one.”

“And that is?”

“To catch them smuggling those diamonds and arrest them with the evidence in their possession, which will send them to prison for many years,” replied Old King Brady.

CHAPTER IX.

Crossing the border.

As La Croix’s party did not seem to be in any hurry to leave Montreal, the
Bradys had plenty of time to arrange their plans.

On the following day they went to the telegraph office and sent two messages, the first being couched in the following terms: 

     “Collector of Port, N.Y.:  Swear out warrant for arrest of Clara La
     Croix, charge of smuggling, and mail at once to International,
     Niagara Falls.  Brady.”

The second was addressed to the Customs department at Suspension Bridge, saying: 

     “Keep watch for La Croix, wife and daughter with four spies.  Are
     going to attempt to pass $250,000 worth of diamonds.”

As La Croix was well known, details were useless.

The Bradys watched their quarry closely.

Knowing they had those diamonds with them, and that they would very likely play a sharp trick to evade the inspectors, the Bradys were very careful.

Scarcely a move made by the family escaped them.

It soon became apparent to the detectives that an important move was soon to be made, for the four spies were in frequent consultation with the Frenchman and his family.

“They are evidently arranging a plan of action,” Harry commented, as he and his partner traced the men to La Croix’s room for the fourth time.

“I wish there was some way of getting a clew to their design,” Old King Brady replied, in wistful tones.  “We are completely in the dark.”

“That’s a sheer impossibility,” Harry answered.  “They are taking the most extraordinary care not to let anyone hear a word they are saying or see a thing they are doing.  I’ve tried several times, and failed.”