Shafer, and Cornelius Witters, the four boys who had embarked on the trip, were sitting snugly around a coal fire in the cabin. They were sturdy, healthy, merry-hearted lads of about sixteen, all from Chicago, and all without family ties of any kind so far as they knew. They had been reared in the streets of the big city, and had become possessed of the Rambler by a series of adventures which the readers of the previous volumes of this series will readily recall.

The night grew darker as it grew older, and a strong wind came up from the bay, bobbing the Rambler about drunkenly. Clayton Emmett—always just “Clay” to his chums—arose from his chair after a particularly fierce blast from the wind and approached the cabin door.

“Don’t open that door!” shouted Alex Smithwick. “We’ll be sent smashing through the back wall if you do. This night makes me think of a smiling summer day in Chicago harbor,—it’s so different!”

“Company!” Clay answered, excitedly, “We’re going to have company. Listen!”

“Yes,” laughed Jule Shafer, “I’ve got a flashlight of any one rowing out to us to-night. The river is too rough for a rowboat.”

“Now you look here, Captain Joe,” Clay went on, “don’t you go start anything!”

This last remark was made to a white bulldog of sinister aspect which had arisen from a rug in a corner of the cabin and now stood at Clay’s side, growling threateningly. Joe wagged a stumpy tail in acknowledgment of the advice, but dashed out, snarling, as Clay opened the door and gained the deck.

“All right; go to it!” Alex laughed, as the door closed behind the two. “Stick out on deck a spell and the wind will do the rest.”

Case Witters—he was never anything but “Case” to his friends—went to the door and looked out through the blurred glass, wiping the inside of the panel with his sleeve in order to get a clearer view.

“What’s coming off?” demanded Jule.

“I hope we’ll be able to get away on one trip without some one butting in,” suggested Case.

“Say, now, look at Teddy,” cried Jule, springing to his feet.

“Teddy” was a quarter-grown grizzly bear. He had been captured on the Columbia river, and had been a great pet of the boys ever since. He now rose from the rug which he had occupied in company with Captain Joe, the white bulldog, and shambled over to the door, against which he lifted a pair of capable paws in an effort to get a view of the deck.

“Rubberneck!” called Alex, digging the cub in the ribs.

“You know what you’ll come to if you talk slang!” Jule grinned. “You’ll have to wash dishes for a week. We all agreed to that, you know,” he added as Alex wrinkled a freckled nose and pointed to the bear cub still trying to look out.

“Why don’t you let him out?” he asked. “If the wind blows his hide off, we’ll make a rug of it. What is Clay doing?”

Case did not reply to the question. Instead, he opened the door, swinging it back with a bang, and both boy and bear ran out on deck. The first thing Teddy did was to sit up on his hind legs and box at the wind, which rumpled his fur and brought moisture to his little round eyes. Boxing was one of the accomplishments taught him by the boys, and he took great pride in it.

Alex closed the door and, with Jule at his side, stood looking out on deck. Clay, Case and the two pets stood at the prow, gazing down on the river.

Directly the top of a worn fur cap made its appearance above the gunwale of the boat, followed almost immediately by the head and shoulders of a man. Then Alex and Jule both rushed out of the cabin.

“He must be a peach, whoever he is, to come off to us in a canoe over that rough water to-night!” Alex cried. “I want to see that boat of his.”

The boat in which the stranger had put off was rocking viciously in the stream, and it was some seconds before he could secure a footing which promised a successful leap for the deck. When at last he came over the rail, the boys saw a heavily-built man with thin whiskers growing out of a dark face. His eyes were keen and black, and the hair hanging low down on his wide shoulders, was black, too, and straight.

Holding his boat line in one hand, in order that the craft might not drift away, he searched with the other hand in the interior pockets of a rough Jersey jacket for a second, and then brought forth a sealed package which he handed to Clay. As the boy took the package, the man who had delivered it sprang, without speaking a word, to the railing, hung for a moment with his feet in the air above the bobbing canoe, dropped, and was almost instantly lost in the darkness.

Leaning over the railing of the boat, wide-eyed and amazed, the four boys stood for a moment trying to pierce the line of darkness beyond the round circle of the prow light. Nothing was to be seen. The boat had come and gone in the darkness. The packet in Clay’s hands was the only evidence that it had ever existed. Alex was the first to speak.

“What do you know about that?” he shouted.

“They must have fine mail facilities on the St. Lawrence!” commented Case.

“That was only a ghost!” Jule asserted, with a wink at Alex. “That letter will go sailing up in the air in a minute.”

Clay opened the packet so strangely delivered and unfolded a crude map of a country enclosed between two rivers. These rivers, after running close together for a long distance, spread apart, like the two arms of a pair of tongs, at their mouths, making an egg-shaped peninsula which extended far into the main river. Back from the river shore, on this rude drawing, a narrow creek cut through the territory between the two rivers, making the peninsula an island.

Below this rude drawing of the rivers and the peninsula was another of an old-fashioned safe resting high up in a niche in a rocky wall. The face of the wall was cross-hatched, to show that it was in the shadows.

Below the drawing of the safe, were these words:

“At last! Follow instructions. Success is certain. Map enclosed. Point straight to the north.”

The boys gathered closely around Clay, standing under the brilliant prow light, and examined the paper, passing it from one to another with questioning glances.

“I guess,” Alex said, “that we are drawing somebody else’s cards.”

“Well,” Case suggested, “that’s a queer kind of a hand to come out of the night.”

“Perhaps,” Jule observed, “they present travelers on the St. Lawrence with these little souvenirs just to excite interest.”

“Point straight to the north,” repeated Clay. “I wonder what that means.”

“I’d like to know what any of it means,” Alex asserted. “It looks to me like some one was butting in.”

“Well,” Case remarked, “we have started out on every trip with a mystery to unravel, and here we go again, loaded up with another.”

“You bet we have!” laughed Alex. “We harvested gold on the Amazon, caught murderers on the Columbia, found a secret treasure in the Grand Canyon, and chased pirates on the Mississippi, but this is the only real Captain Kidd mystery we have struck yet.”

“What shall we do with it?” asked Clay, rattling the paper.

“Throw it in the river and be on our way,” proposed Case.

“Suppose,” Alex grinned, “there should be a barrel of money in that safe they’ve made a drawing of. If there is, we want to get it.”

“I think we’d better be going on, just the same,” Case said. “I’m for dumping this map thing into the river and forgetting all about it.”

“Aw,” Alex cut in, “that would be throwing away all the fun. I want to go to this ‘North,’ wherever it is. There may be something funny doing there.”

Captain Joe, who had been sitting at the prow, watching the boys with an intelligent interest, now passed back to the cabin, leaped upon the low roof,