III
“But you’re safe—it’s all over now,” reminded Gildersleeve handing the detective a cigar. “The question is did you find out anything worth while?”
“I found out something that ought to be worth a whole lot.”
“Good!” urged Gildersleeve. “I told you there was a fifty-dollar bonus in it if you got a line on the North Star’s secret layout and their wireless plant up there. That promise holds.”
“I don’t know what’s up in that devilish place,” remarked Lynch, “but I did find out how they get in and out of the Cup of Nannabijou.”
“What!” Both Gildersleeve and Duff were tense. “It’s a creek-bed that dries up when you touch a button.”
His companions stared blankly as though he had suddenly gone crazy.
“S’help me,” insisted Lynch, “that’s just what it is. I found it out by pure accident. Was poking around in a sort of tunnel that opens out on the rapids of the creek when my foot caught in something, and, in trying to stop myself from falling, I swung up a hand against a piece of rock jutting from the wall. In my business I keep my fingers as sensitive as a combination lock expert. I guess if it hadn’t been for that I wouldn’t have felt that little round hole in the rock. I got out my pocket-flash and examined it. It was only about the size of a nail, drilled into the rock about an inch and a half. I could see then that that knob of rock had been cleverly cemented into a hole in the wall. ‘A’ha,’ thinks I, ‘this is a spring that opens some secret entrance through the rock.’ I wasn’t at all expecting what it really turned out to be. So I gets a match, inserts it in the hole and presses down on it just to see what would happen.
“There was a flash like lightning, and a queer, soft sound like a gong came from up above somewhere. Then in a minute it seemed to me the creek rapids just down the tunnel got awful quiet.
“I went down to investigate, and sure enough there was no water running down, and if it hadn’t been for the wet at the bottom and sides of the channel I wouldn’t have believed there ever had been. I slipped back and pressed the match against the concealed button again. The bell rang and almost right away the water came roaring down like it was before. Now I think that was pretty good scouting for one day.”