[Illustration] "Hey! What's the big idea?" the man stammered. "I ain't done nothing. Just got a phone call this morning, offering me fifty bucks to bring two sets of clothes down to the beach at five o'clock for a couple of divers." "Tell that to the FBI!" snapped the sergeant. When the officers had departed with their new prisoner, Bud and Mel, both grinning, dived into the surf and headed out to sea. In a few minutes they were sure they were at the right spot to meet the jetmarine. But it was gone! CHAPTER XIV A PROPAGANDA BLITZ As the _Sea Hound_ returned to Fearing Island from its search for Bud's jetmarine, Tom was beside himself with worry. Had his experiment cost the lives of his best friend and the other crewmen aboard? "I'll never forgive myself if anything's happened to them!" Tom muttered bleakly. Hank Sterling squeezed the young inventor's arm. "You know Bud's high spirits, skipper," he said. "He may have taken off on some crazy lark." "Sure! A whale hunt, maybe!" Arv Hanson wisecracked, trying to lighten the gloom. Tom forced a grin, but he remained heavy-hearted as they neared the base. His only hope now was that a radio message from the jetmarine might have been picked up while they were gone. As soon as the seacopter was moored, Tom leaped ashore. The crewmen on the docks had no news to report, so Tom piled into a jeep with Arv and sped off to the Fearing communications center. Hank remained aboard the _Sea Hound_ to secure all gear. Churning along the graveled road, Tom and Arv passed the launching area. Huge, needle-nosed cargo rockets and the mighty spaceship _Titan_ loomed against the sky. Tom's moon-voyaging _Challenger_ and his more recent space craft the _Cosmic Sailer_ were also based there. "Going to alert the Navy for a search?" Arv inquired as they reached the communications building. Tom nodded and braked the jeep to a screeching halt. "Coast Guard too. They can pass the word to commercial shipping to be on the lookout." A telephone rang as he hurried into the office. "For you," the clerk said, looking up at Tom. "Nice timing!" Tom grabbed the phone. His face widened into a grin. "Bud! You seagoing jet stream! What happened?" Arv grinned, too, in relief. "Your antidetection gear worked so well we vanished right out of the ocean!" Bud replied with a chuckle. Turning serious, he reported how his jetmarine had trailed the mysterious intruder and how he and Mel had captured the two Brungarian frogmen and their shore contact. "Nice going, pal!" Tom exclaimed. "But here's the catch," Bud went on. "When we took off again in our hydrolungs to go back aboard ship, the jetmarine was gone!" "Maybe she's trailing the enemy sub," Tom conjectured. "That's what I'm hoping," Bud said uneasily. "Trouble is, our subs aren't armed, and who knows about that Brungarian job? The way they sling missiles around, anything could happen if she spots the jetmarine."