"Large number of enemy aircraft reported flying over North Sea, fifty miles south of you, every night. Investigate.
(Signed) "BEATTY."
Jack passed the slip of paper back.
"Well?" exclaimed Captain Raleigh.
"Yes, sir," replied Jack. "You want me to find out what's going on, sir?"
"Exactly. Can you run a hydroplane?"
"No, sir; but Frank here can."
"Who?"
"Lieutenant Chadwick, sir."
"Oh," said the commander, "so he is Frank, eh? All right. Then here is what I want you two to do. Take the hydroplane aft and fly south. Take your time and see what you can find out. The matter may amount to nothing, and then again it may forebode something serious."