"Captain, who are the four silent men leaning over the rail on the other side of the boat?" asked Tad Butler. "I have been wondering about them almost ever since we left Vancouver. They don't seem to speak to a person, and seldom to each other, though somehow they appear to be traveling in company. They act as if they were afraid someone would recognize them. I am sure they aren't bad characters."Captain Petersen, commander of the steamer "Corsair," which for some days had been plowing its way through the ever-changing northern waters, stroked his grizzled beard reflectively."Bad characters, eh?" he twinkled. "Well, no, I shouldn't say as they were.They're fair-weather lads. I'll vouch for them if necessary, and I guess I'm about the only person on board that knows who they are."Tad waited expectantly until the skipper came to the point of the story he was telling."They are the Gold Diggers of Taku Pass, lad.""The Gold Diggers of Taku Pass?" repeated Tad Butler. "I don't think I ever heard that name before. Where is this pass, sir?"The skipper shook his head."No one knows," he said."That is strange," wondered Butler. "Does no one know where they dig for gold?""No. They don't even know themselves," was the puzzling reply.Tad fixed the weather-beaten face of the skipper with a questioning gaze."I don't think I understand, sir."