"No sign of him," Joe said, looking up and down the street.  "He could be anywhere by now."

Frank nodded glumly.  "You're right.  We lost him."

The boys returned to the club and picked up Chet, then went to their room.  It overlooked the alley and had a fire escape under the window.

"Good," Chet declared when he noticed the exit.  "We can get out of here in a hurry if we're cornered by crooks.  Say, how about chow?  I haven't eaten since breakfast.  I might faint."

"If you do, you'll shake up the club," Joe quipped.  "It wasn't built for your weight."

Chet looked pained, but Frank came to his rescue.  "I'm with you, Chet.  It's dinnertime anyway."

The boys freshened up a bit, then went to the dining room.  After giving the waiter their order, Chet leaned back in his chair.  "Well, Hardys," he grinned, "do you have a plan for solving the big mystery yet?"

"We're working on it," Joe said, sipping water from his glass.

"I think Jenson was kidnapped by a foreign power," Chet declared.

"Maybe he worked for a foreign power and left on his own," Joe put in.

"You mean as a spy?" Chet asked.

Joe nodded.  "Perhaps he developed the Firebird Rocket and sold the secret to someone else."

Frank shook his head.  "But why would he wait until the United States finished building the missile?  I think he would have given away the secret earlier and stolen the plans in order to prevent us from completing the project."

Chet nodded.  "I'm with Frank.  The spy angle doesn't seem to fit in this case.  Jenson was probably kidnapped."

"So where do we start with our work?" Joe wanted to know.

"We interview all the people at the lab," Frank said.  "Let's hope somebody there will be able to give us a line on that bearded creep."

The boys discussed their strategy during dinner, and after they had dessert, Chet suggested that they go for a walk to clear their heads.

"I have a better idea," Joe said.  "I noticed a sign saying that there's dancing after dinner.  Why don't we listen to the music for a while?"