“You don’t seem curious about your letter, Captain,” smiled Ida, when she had glanced through two of her own.

“Is one ever curious or eager about bills?” laughed Tom. “I’ve three or four accounts down in Tres Arbores for supplies furnished for the boat. But I can’t settle any of them until we go back to the bay.”

As the air was growing somewhat chilly, with the sinking of the sun, the others passed on into the living room, where Ham had a blazing wood fire ready for them. Tom, however, remained outside, preferring the fresh air.

After strolling about the grounds for some little time, he stepped into an arbor. It seemed curious to this Northern boy to think of a leaf-clad arbor in December, but here it was, with vines growing luxuriantly over the trellis work. There was a seat there, and Tom sank onto it. He was thinking hard about the robbery in the starboard stateroom on the morning of their arrival in Oyster Bay. No more had been said about it by any member of the party, yet with Tom Halstead the subject would not down.

“Of course, the Tremaines and Miss Silsbee must often remember that I was the only one outside their party who had access to the cabin during the night of the storm,” he mused. “They’re all mighty kind to me, yet what must they think when they sometimes get to wondering? Of course, Oliver Dixon was the scoundrel. I saw him fix the contents of the water bottle from that vial of his. He knew that only Mr. Tremaine drank water just before turning in. Dixon robbed his friend, after drugging him. Yet what a wild story it would be, backed by no word but my own. Joe is right; I’ve got to hold my tongue and be patient. Mr. Tremaine would think it all a cock-and-bull story if I told him what I saw Dixon doing. Gracious, but it’s hard to keep quiet and wait. The truth most likely will never come out—and there’ll always be that lurking suspicion of me!”

After some minutes Halstead remembered the letter from Tres Arbores. Some instinct prompted him to take it out and open it. Instead of being a bill, as he had suspected, it was a letter.

“Jumping bow-lines!”

Tom Halstead was fairly staggered as he glanced through that short epistle in the waning light of day. The letter was signed by Clayton Randolph, the policeman at Tres Arbores, and it ran:

I am taking this chanse of writing you, as I know the mail goes up to-day. I am on board your boat most the time, all is well there. Now I have something to tell you I know will intrest you. You remember the afternoon of the day you landed here, you and partner stayed here in the afternoon, but Tremane and his party drove over to Tunis that afternoon. Dixon must found a chanse to slip the rest of the party, for he went to the xpress office and sent a package to Ninth National Bank New York, said the value was 3200 dollars. Maybe real value was more but he thought that enough to make xpress people careful. Now it happens my oldest boy, Joe, is xpress agent at Tunis. He was down here to-day and when he heard about robbery he told me about Dixon sending package. Maybe you can put two things together. I tell you this because I like you and believe you’re straight.

Tom Halstead read this illuminating missive over slowly, aloud, with growing wonder in his voice.