nger jotted the names on the back of an envelope. Pausing a moment, he
remarked, "Guess your brother was too busy to make it today, eh, Miss
Swift? What kind of ex-spearmints is he working on now?"

"I really couldn't say," Sandy replied coldly. She always made it a
point not to discuss Tom Jr.'s or her father's research work with
outsiders.

Unger persisted chattily, "I read where he handled that Jupiter probe
shoot for the Navy."

"Let's get back to square dancing," snapped Bud. As he and Sandy
finished planning the program, Len Unger continued to drop remarks and
questions about "The Great Tom Swift" and his inventions. All prying
queries were side-stepped.

As soon as possible Sandy and Bud cut short the conversation and left
the yacht club. Unger's face wore an angry sneer as they walked out.

"What a creep!" Bud said, when he and Sandy were driving back in his red
convertible.

Meanwhile, in his private laboratory at Enterprises, Tom was somewhat
discouraged. He had tried several different experimental attacks on the
problem of an undetectable submarine. None had worked out successfully.

"I thought that idea of a sonar-wave baffle might lead somewhere," he
murmured, "but it looks as though I'm wrong."

Flopping down on a stool at his workbench, Tom cupped his chin in his
hands. He was frowning, deep in thought, as the pudgy figure of Chow
Winkler came into the laboratory.

"'Smatter, boss?" the cook inquired cheerfully. "Ain't your ole think
box workin' today?"

"Doesn't seem to be," Tom confessed.

"Give it time, son. Tomorrow's another day," Chow said philosophically.
"What you need is a haircut for the square dance."

Tom laughed in spite of himself. "Maybe you're right, Chow. Might help
me think better."

Tom got off the stool and stretched out the kinks in his legs. He
strolled outside with Chow, then scootered to the parking lot and hopped
into his sleek, silver sports car.

A moment later he was whizzing off in the direction of Shopton. Nearing
town, Tom turned off on a side-road short cut. He noticed in his mirror
that a truck behind him also turned off.

"Really barreling along!" Tom thought. "If you're in such a hurry, the
road's yours, pal."

He pulled over sharply, motioning the truck to pass. Instead, to Tom's
surprise, it closed in straight behind him. The next moment, Tom saw a
port open below the truck's hood and a strange-looking device pop out on
a springlike steel cable.