The Disappearing Floor by Franklin W. Dixon Page A

a nice, clear-cut alibi for himself.”
    As soon as they arrived home, the boys developed the film and made an enlarged print of the chart. As expected, it showed the Bayport coastal area. A notch in the coastline south of Barmet Bay had been circled in pencil.
    â€œIt’s the place on Clams Daggett’s map—Tigers’ Bight!” Frank exclaimed, then frowned. “I don’t get it, Joe. Hirff knew we’d heard about Tigers’ Bight, and we were bound to locate it. So why was he so eager to get the film back?”
    â€œYou’re overlooking something, Frank—right here.” Joe pointed to an X mark near the bight, barely visible on the print.
    Frank gave a whistle. “Wonder what’s there!”
    â€œMaybe enough evidence to put the gang behind bars,” Joe surmised. “This photo would link them to whatever that X stands for.”
    â€œWow!” Frank was jubilant. “I have a feeling we’re really getting somewhere now, Joe!”
    â€œIf only we knew what those words on Jack’s phone pad meant—‘Amethyst calling Seacat.’ ”
    â€œSounds like a radio call,” Frank mused. “It would tie in with our guess about ‘Seacat.’ ”
    â€œIn other words, a radio call to a boat.”
    â€œRight. But the ‘Amethyst’ part stumps me—unless that’s the name of another boat—or maybe of a plane that’s doing the calling.”
    â€œThat’s it, Frank!” Joe snapped his fingers excitedly. “It could be a code name for Jack’s own plane—or even for Jack himself!”
    â€œRight. Let’s assume Tom Lester’s hunch is correct—that Jack managed to worm his way into Hir$’s gang. And let’s assume your hunch is correct that he was flying to Tigers’ Bight.”
    â€œOkay. So what then?” Joe asked.
    â€œDon’t you see? Maybe Jack was flying there on Hirff’s instructions. Hirff told him to contact a boat named the Seacat by radio and then rendezvous with it in Tigers’ Bight!”
    â€œPerfect!” Joe exclaimed. “Frank, if Jack was flying a mission for the gang, that radio message wasn’t sabotaged. It must have been interrupted accidentally.”
    â€œI’ll check right now!” Frank said. He called the Bayport radio station and learned that it, too, had experienced freakish transmission difficulties the day before—apparently due to sunspots.
    â€œFrank, let’s go to Tigers’ Bight and find out what that X stands for,” Joe proposed. “While we’re at it, we may spot Jack’s plane!”
    â€œOkay,” Frank agreed. “But let’s call Dad first. He may be back at the hotel by now.”
    The boys were able to contact Fenton Hardy. “How’d you make out in Gary, Dad?” Frank asked.
    â€œWe ran into a blank wall,” the detective replied. “The getaway car was traced there. But I’m sure now it was just a false scent to make us think the thieves had fled to that area to hide out.”
    When Mr. Hardy heard about the Haley Building mystery and the vanished diamonds, he concluded that the same jewel thieves had struck again.
    â€œSam and I had better fly back there as soon as possible,” he told Frank. “We’ll try to be in Bayport sometime tonight.”
    Mr. Hardy listened with keen interest to Frank’s report about Al Hirff, the notation on Jack’s phone pad, the gas-bomb attack on the boys, and their theory about Tigers’ Bight.
    After concluding the conversation, the boys drove to Bayport harbor. They rented a motorboat and started into the bay. As they passed the jetty, they sighted the Napoli, with Tony and Chet aboard.
    The boys hailed one another, and brought their boats alongside. Frank told them where he and his brother were heading.
    â€œWhy pay rent on that job?” Tony exclaimed eagerly. “I’ll