He grabbed a pencil and began sketching his idea on paper. It would be necessary to spot the receivers and transmitters all over the hull of the submarine. Diagrams and pages of scribbled computations followed the rough sketches.

An invisible sub--one that sonar pulses would seem to pa.s.s right through, as if nothing were there! "Seems so simple now that I have the key!" Tom said to himself elatedly.

Hours ticked by while he a.n.a.lyzed the wave action mathematically, then worked out a typical hookup for one of his jetmarines in a set of precise schematic drawings.

Finally the young inventor dropped his pencil, picked up the telephone, and dialed Bud Barclay.

"Hop over here, fly boy," Tom told his chum. "Something hot on the griddle!"

Bud arrived in a few moments. Tom showed him the drawings and explained his plan for dodging underwater detection. He also related how Chow's remarks about the radio music had sparked the idea.

His chum slapped him on the back. "Good going, Tom!"

"Let's fly right over to Fearing and see how it works on a jetmarine!"

Tom proposed enthusiastically.

Bud grinned but made no move. He stood looking at Tom, arms folded and feet wide apart.

"Well, let's go, pal!" Tom urged impatiently, puzzled by Bud's lack of response.

"What about the square dance?"

Tom stopped short, feeling like a punctured balloon. He stared in dismay at his smiling, dark-haired copilot. "Good night! I forgot again!"

With a sigh, Tom added, "You're right, of course. We sure can't let the girls down twice. But at least let's get together all the gear we'll need when we _do_ go to Fearing."

"I guess we'll have time for _that_," Bud conceded with a sympathetic grin.

Tom a.s.sembled a ma.s.s of electronic equipment and phoned various Enterprises' departments for other items. Bud helped to collect them, and the boys trucked the paraphernalia out to a hangar to be loaded aboard a Whirling Duck. Then they scootered back to the lab for a quick shower and change.

Twenty minutes later, in sport jackets, checked shirts, and slacks, the two chums hopped into Bud's red convertible. They picked up Sandy and Phyl and drove a little way into the country for dinner at a huge old farmhouse restaurant.

"Well, the evening's off to a good start," Sandy said with a happy laugh as they headed back along the lakesh.o.r.e road to the yacht club.

"Hope I didn't put away too much fried chicken to sashay properly at the square dance," Bud remarked.

Tom chuckled. "Don't worry, pal. You always untangle those feet of yours when the fiddle strikes up!"

The blazing lights of the yacht club were reflected in the blue-black mirror of the boat basin. Bud parked and they went inside.

"Welcome, buckaroos!" Chow Winkler greeted them with an enthusiastic bellow as they entered the dance room.

The old cowpoke was splendidly dressed in a maroon satin shirt and white whipcord breeches tucked into shiny new boots. But instead of his usual sombrero, a chef's cap was perched on his head.

"Chow! You look marvelous!" Sandy said.

The cook blushed with pleasure. "You gals look purty enough to charm a hoot owl right off'n his perch!" he shot back. Both Phyl and Sandy were wearing gay calico dresses that had full swirling skirts.

The room was decked out with colored bunting and twisted crepe-paper streamers. And at one end of the dance room, Chow had rigged up a model of a Western chuck wagon.

"Real atmosphere!" Tom said admiringly. "Chow, you've done us proud!"

"Thanks, boss." The cook, who had asked especially to take charge of the decorations, glowed at the praise. Then he became serious. "But what's keepin' that dad-blamed fiddler?"

The guests soon began to stream in, but half an hour went by, and Lester Morris and his fellow musicians had not arrived.

"I'd better phone his house," Tom decided worriedly.

Mrs. Morris answered. She seemed surprised at Tom's call. "Why, my husband's playing at a party over in Carterton this evening," she said.

"Are you sure you engaged him for tonight?"

"I'm positive," Tom replied.

"Just a moment, please. I'll look in his date book to see if there's been a mistake."

A minute later her voice came over the line again. "I'm terribly sorry, Mr. Swift, but your name isn't listed anywhere on Lester's schedule."

The others saw from Tom's face as he hung up that something was wrong.

"What gives?" Bud asked anxiously.

"No music for one thing." Tom reported what Mrs. Morris had told him.

"But you hired the guy!" Bud protested. "And Sandy and I talked to his agent!"

Tom was already piecing together the mystery. He shook his head thoughtfully. "I'm sure now the whole deal was a hoax, Bud," he declared. "Both the first call that supposedly came from Lester Morris, and the second one asking me to come here and talk things over."

By not responding to the second call in person, Tom went on, he had probably saved himself from being waylaid or kidnaped by his enemies.

"Thank goodness!" Sandy exclaimed. "Still, that creepy Len Unger was trying to get information from us."

"But how did your enemy know about the dance, Tom?" Phyl Newton put in.

Sandy snapped her fingers. "I know! I'll bet it was when we went shopping for our dresses, Phyl, right after the boys invited us! The department store was full of people--almost anyone might have heard us discussing the dance!"

"Especially if he was already trailing you to pick up bits of useful information," Tom agreed.

Bud whipped out a handkerchief and mopped his face nervously. "The question is what do we do now, chums? A roomful of guests and no music!"

"Relax, pardners!" Chow broke in cheerfully. "Just keep things goin' for a spell, an' I'll fix things up p.r.o.nto!"

Doffing his chef's cap, Chow hustled out to his parked jeep and took off with a roar. Mystified but hopeful, Tom, Bud, and Phyl did their best to entertain the guests. Sandy had rushed to the telephone. In twenty minutes Chow came rushing back.

"Hey! He has a fiddle!" Bud exclaimed.

Mounting the platform, the stout cowpoke raised his hands and shouted for attention.

"Ladies an' gents, we'll start off with that good old dance known as the Texas Star!"