"What sort of clue, sir?" Tom asked.
"A compressed-air caisson for underwater work. It had been driven into the silt and then abandoned." Admiral Walter added that photographs and a section of the caisson were being flown to the Naval Research Laboratory for careful study. "I'll have a full report transmitted to you by video as soon as it reaches my desk."
Tom thanked the admiral and hung up, feeling more uneasy than ever. The report came through the following morning. Tom absorbed the contents, then gave a low whistle.
"Trouble?" asked Bud, who had just dropped into the office with some flight-test data on a new Swift superjet.
"Our old enemies again." Tom shoved the papers across his desk.
The report stated that both the design and manufacturing techniques used in making the caisson indicated that it was of Brungarian origin. A spectrographic analysis of the steels confirmed the theory. Their metallurgical content agreed with known Brungarian steel formulas.
"The sneaky rats!" Bud cried out. "Well, at least we know now who sabotaged our missile recovery."
As Tom paced about the office, Bud added, "What do you suppose they were using the caisson for?"
"Probably as a base for some heavy, rotating search equipment," the young inventor surmised.
"But why ditch it?"