“I don’t suppose you know,” he explained, lowering his voice, “but since these negotiations began, the consular service has been keenly interested in the present state and the possibilities of the islands.  The government sent one special agent there, named Dwight.  Well, he died a few days ago.  It was very suspicious, so much so that the authorities in the island investigated.  Yet the doctors in the island have found no evidence of anything wrong, no poison.  Still, it is very mysterious—­and, you know,” he hinted, “there are those who don’t want us down there.”

The Secret Service man paused as though he had put the case as briefly and pointedly as he could, then went on:  “I’ve been assigned to accompany the new consul down there and investigate.  I’ve no particular orders and the chief will honor any reasonable expense account—­but—­” He hesitated and stopped, looking keenly at Kennedy’s face.  I saw what he was driving at.

“Well—­to come to the point—­what I wanted to see you about, Kennedy, is to find out whether you would go with me.  I think,” he added, persuasively, “it would be quite worth your while.  Besides, you look tired.  You’re working too hard.  The change will do you good.  And your conscience needn’t trouble you.  You’ll be working, all right.”

Burke had been quick to note the haggard expression on Kennedy’s face and turn it into an argument to carry his point.  Kennedy smiled as he read the other’s enthusiasm.  I would have added my own urging, only I knew that nothing but a sense of duty would weigh with Craig.

“I’d like to think the proposal over,” he conceded, much to my surprise.  “I’ll let you know in the morning.”

“Mind,” wheedled Burke, “I won’t take no for an answer.  We need you.”

The Secret Service man was evidently delighted by the reception Kennedy had given his scheme.

Just then I caught sight of the party of four getting their hats and wraps preparatory to leaving, and Kennedy eyed them sharply.

Marlowe and Whitson passed.  As they did so I could not help seeing Whitson pause and shoot a quick glance at the four.  It was a glance of suspicion and it was not lost on Craig.  Did they know more of this Mexican gun-running business than Marlowe had hinted at?  I watched Kennedy’s face.  Evidently his mind was at work on the same idea as mine.

Burke accompanied us almost all the way home, with Sydney adding his urging.  I could tell that the whole combination of circumstances at the Burridge had had an effect on Kennedy.

I went to bed, tired, but through the night I knew Craig was engaged on some work about which he seemed to be somewhat secretive.  When I saw him again in the laboratory, in the morning, he had before him a large packing-case of stout wood bound with steel bands.

“What’s that?” I asked, mystified.  He opened the lid, a sort of door, on which was a strong lock, and I looked inside.