"Take out your ID card. Separate the two pieces of plastic. There's a flat plastic key next to the card. Open the brief case lock with it." The voice was silent until Don, with the help of a razor blade, had done as he was directed. "All right, sir; that's done." "Open the brief case, take out the package, open the package and put the wrappings back in the brief case." Again the voice stopped. Don unwrapped something that looked like a flat cigarette case with two appendages, one a disk of perforated hard rubber the size of a half dollar, and the other a three-quarter-inch-wide ribbon of opaque plastic. "I've got it, sir." "Good. What you see is a highly advanced radio transmitter and receiver. You can imagine its value in the field. It's a pilot model you were bringing back from the contractor for tests here. But this seems as useful a way to test it as any other." "It's range is fantastic, Captain--if you're in Washington." "I am. Now. The key also unlocks the handcuff. Unlock it. Strip to the waist. Bend the plastic strip to fit over your shoulder--either one, as you choose. Arrange the perforated disk so it's at the base of your neck, under your shirt collar. The thing that looks like a cigarette case is the power pack." Don followed the instructions, rubbing his wrist in relief as the handcuff came off. The radio had been well designed and its components went into place as if they had been built to his measure. They tickled a little on his bare skin, that was all. The power pack was surprisingly light. "That's done, sir," Don said. The answer came softly. "So I hear. You almost blasted my ear off. From now on, when you speak to me, or whoever's at this end, a barely audible murmur will be sufficient. Try it." "Yes, Captain," Don whispered. "I'm trying it now." "Don't whisper. I can hear you all right, but so could people you wouldn't want overhearing at your end. A whisper carries farther than you think. Talk low." Don practiced while he put his shirt, tie and coat back on. "Good," Captain Simmons said. "Practice talking without moving your lips, for occasions when you might have to transmit to us in someone's view. Now put your handcuff back on and lock it." "Oh, damn," Don said under his breath. "I heard that." "Sorry, sir, but it is a nuisance." "I know, but you have to get rid of it logically. When you get a chance go to the local bank. It's the Superior State Bank on McEntee Street. Show them your credentials from Riggs National and ask them to keep your brief case in their vault. Get a receipt. Then, at your first opportunity, burn the plastic key and your ID card." "Yes, sir." "Keep up your masquerade as a bank messenger and try to find out, as if you were an ordinary curiosity-seeker, all you can about Cavalier Institute. You've made a good start with the Garet girl. Get to know her father, the professor."