Chow's fondness for experimenting with weird dishes was a standing joke around Enterprises. The boys ate their meal hungrily. As they were finishing, Tom glanced at the big clock on the wall. It was now well past eight o'clock. "Wonder why Dad hasn't come to the lab," he remarked. "I'd better call and find out if he's all right." Tom picked up the telephone and asked the operator for the direct line to the Swifts' home. His father answered. "'Morning, Dad!" Tom greeted him. "I thought after your call last night, you'd be over bright and early to see our visitor. He's already--" "What are you talking about, son?" Mr. Swift broke in. "I didn't phone you last night!" CHAPTER XIII DISASTER STRIKES Tom was thunderstruck. "You didn't phone me? But, Dad, I got the call--I definitely heard your voice!" "That's impossible," Mr. Swift insisted. "Believe me, son, I slept soundly from the time I turned in until a little while ago." There was a moment of stunned silence as both Swifts realized that the telephone call had been faked! Then Tom exclaimed: "Dad, this is serious!" "Deadly serious, I agree," his father replied. "Are you calling from your lab?" "Yes!" "Stay there. I'll be right over," the elder scientist said. When Mr. Swift arrived, Tom related his conversation with the mysterious caller. His father listened with worried eyes and a puzzled frown. "It's bad enough that an enemy was able to get the information," Mr. Swift remarked. "But, potentially at least, it's even more dangerous that he was able to imitate my voice so well. If he could fool you, Tom, he could fool anyone!" "Are you thinking the same thing I am, Dad?" "That it may have been some insider here at Enterprises?" When Tom nodded, his father gravely agreed. "Yes, son, it does look that way. To imitate my voice convincingly, it would almost certainly have to be someone who's had close contact with us--either at the plant or here in Shopton." The thought of a traitor at the experimental station was repugnant to the Swifts and to Bud as well. Not only were all employees carefully screened, but there was a close, almost family relationship among those who took part in the exciting scientific ventures at Swift Enterprises. Tom called Security and asked Harlan Ames to come over to the laboratory at once. The security chief arrived within moments. Quickly Tom filled him in on the details of the puzzling telephone call. "Think back, skipper," Ames urged. "Was there anything at all you can remember about the voice that might give us a tip-off? I mean, was it deep, or maybe a bit higher-pitched than you expected? Or anything about the way the caller pronounced his words?" Tom shook his head. "Nothing. That's the trouble. He spoke only a couple of sentences, but so far as I knew, it _was_ my father calling!" "Hmmm." Ames frowned. "What about background noises?"