The Secret Agent on Flight 101 by Franklin W. Dixon

won’t talk to you lunks. I’ve said too much already!”
    Joe spoke up. “Don’t get so nasty, Timken. You forget that my brother saved your life. What kind of gratitude is this?”
    Still no reply.
    â€œListen, buddy,” Joe continued, “you know you’re going to prison for trying to kill the rest of us. You might get a lighter sentence if you answer a few questions. For instance, what was your racket on the Great Circle flights?”
    â€œI won’t squeal!” Timken shouted, and clamped his lips together.
    Joe shrugged. “Have it your way.” The boys left their prisoner.
    The plane landed at Stornaway and was quickly unloaded. After a conference, McHugh and the boys decided to return the UGLI agent to Ianburgh. On the return trip the pilot adjusted his course so the boys could take more aerial shots of Hexton’s castle.
    Back in Ianburgh, the Hardys handed their prisoner over to the chief constable, who was thunderstruck at the bomb story. He then let them develop their latest photographs. Frank spread the prints out on a table and they all scrutinized them closely. But the pictures revealed no clues.
    â€œThe ground around the castle is as clean as a whistle,” Joe observed. “We couldn’t possibly sneak up on the place without being seen.”
    â€œWhat about climbing up the surrounding wall?” Chet suggested. “Robin Hood used to do it all the time.”
    â€œNot a bad idea.” Joe grinned. “But it brings us back to the original problem. How do we get inside the fence and up to the wall without being seen?”
    Frank’s brow creased in contemplation. “I’m afraid this is a tough one.” He signed. “Whatever plan we come up with will have to be pretty far out.”
    At that moment Inspector Clyde arrived. He carried a long, slim black umbrella, which he hooked to the coat rack when he entered the room.
    â€œAh, there you are,” the inspector said. “I have some interesting news for you chaps. Mr. Dell telephoned from the States while you were gone. He’s leaving for Scotland immediately. Something very important and highly secret has come up!”

CHAPTER XV
    A Furious Scot
    DELL arrived in Ianburgh that same night and met the boys at the chief constable’s office. There Inspector Clyde ushered them into the interrogation room and the young sleuths told about the capture of Timken.
    â€œGreat work!” the security chief exclaimed. “I’ll want to question him myself before I go back to the States.”
    When Clyde left the room, Frank said, “I understand something important has come up on your end, too.”
    â€œYes,” Dell replied. “Our investigation has turned up a very interesting lead. Timken has been spending a lot of time with another Great Circle steward named Ross. We checked him out thoroughly and learned that he had a record for petty theft under another name. We suspect he’s part of the Hexton-UGLI setup, but that he and Timken were working together.”
    â€œYou mean they were double-crossing Hexton?” Joe asked.
    â€œYes. I doubt if Hexton would dispose of stolen goods in the clumsy way Timken has been doing.”
    â€œI see,” said Frank. “These two manage to hold out a diamond here and there from the gang’s robberies, then sell them.”
    â€œRight. We could pick Ross up on suspicion, of course. But I’d rather give him a little rope. Maybe we’ll get a stronger case on him. Catching him first might make it easier to get Hexton.”
    â€œWhere do we fit in?” Chet spoke up a bit fearfully.
    Dell smiled. “Your assignment is to make a trip to the United States on our Flight 101. Ross will be steward. Use assumed names and occupations on the plane. Watch Ross and see if you can pick up any leads for SKOOL.”
    Joe grinned. “I’ll feel like a secret agent on Flight