Don himself was a last-minute choice, a "channel of opportunity"-the Venus crisis had rushed things. How badly it had rushed things no one knew until after Commodore Higgins' spectacular raid on Circum-Terra. The engineering data so urgently needed on Mars had gone to Venus instead, there to be lost (Don's half of it) in the confusion of rebellion and counterblow. The rebelling colonists, driving toward the same goal as the Organization, had unknowingly thwarted their best chance for overthrowing the Federation.

Communication between the Organization members on Venus, on Earth, and on Mars had been precariously and imperfectly reestablished right under the noses of the Federation police. The Organization had members working for I. T. & T. on all three planets-members such as Costello. Costello himself had been helped to make his escape, with Isobel, because he knew too much; they could not afford to have him questioned-but a new "drop box" had been set up at Governor's Island in the person of a Federation communications technical sergeant. The channel to the sergeant was a dragon who had the garbage disposal contract for the "Greenie" base. The dragon had no voder; the sergeant knew no whistle talk-but a tentacle can pass a note to a human hand.

Communication, though difficult and dangerous, was possible; travel between planets for members of the Organization was now utterly impossible. The only commercial line as yet reestablished was the Earth-Moon run. The group on Venus was attempting the almost impossible task of completing a project all preliminary preparations for which had been made for Mars. The task was not quite impossible-provided they could find the missing half of the message, they might yet outfit a ship, send it to Mars, and finish the job.

So they hoped... and continued to hope until recently, when disastrous news had gotten through to them from Earth-the Organization had been penetrated on Earth; a very senior member, one who knew much too much, had been arrested and had not been able to suicide in time.

And a task force of Federation ships was already on its way to attack the group on Mars.

"Wait a minute!" Don interrupted. "I thought-Mr. Costello, didn't you tell me, back in New London, that the Federation had already moved in on Mars?"

"Not exactly. I told you that I had inferred... that the Federation had taken over Schiaparelli Station, the I. T. & T. branch there. And so they had-to the extent of censoring all traffic and putting a stop to all traffic with Venus. They could do that with a squad of soldiers from the pint-sized garrison they've always had there. But this is an attack in force. They mean to liquidate the Organization."

Liquidate the Organization-Don translated the jawbreakers into real words: kill all the people who were against them. That meant his parents

He shook his head to clear it. The thought did not mean anything to him inside. It had been too many years; he could not see their faces-and he could not imagine them dead. He wondered if he himself had become dead inside, unable to feel things. No matter-something had to be done. "What do we do? How can we stop it?"

"We quit wasting time!" answered Phipps. "We've lost half a day already. Sir Isaac?"

"Yes, my friend. Let us hurry."

The room was a laboratory shop, but of dragon proportions. It needed to be, for it held a round dozen of dragons as well as fifty-odd men and a sprinkling of women. Everyone who could manage it wanted to see the opening of the ring. Even Malath da Thon was there, sitting up in his cell with the aid of his powerdriven corset and with the colors of emotion rippling gently across his frail body.

Don and Isobel had climbed to the top of the entrance ramp, where they could see without being in the way. Opposite them was a large stereo tank, lighted but with no picture growing in it. Below them was a micromanipulator, dragon style; other pieces of apparatus and power tools filled the rest of the room. They were strange to Don, not because they were of dragon construction and for dragon use, for many of them were not-they were strange in the way in which laboratory equipment is always exotic to the layman. He was used to dragon artifacts; the two technologies, human and dragon, had interpenetrated sufficiently that a human, especially one living on Venus, found nothing odd in joints that were wrung instead of welded or bolted, nothing unusual in interlocking ovoids where a man would use screws.

Sir Isaac was at the micromanipulator, his tendrils at the controls; down over his head fitted a frame with eight eyepieces. He touched the control rack; the tank rippled and a picture built in it-the ring, in full color and three dimensions. It seemed to be about eight feet across. The boss of the ring faced out, displaying the enamel-filled initial cut into it-a capital "H" framed with a simple circle of white enamel.

The picture flickered and changed. Only a portion of the initial was now visible, but so greatly magnified that the enamel rubbed into the shallow grooves of the letter looked like broken paving blocks. A shadowy pointed cylinder, out of focus save at its very end, moved across the picture; a great oily globe formed on the end of it, detached itself and settled on the enamel. The "paving blocks" started to break up.

Montgomery Phipps climbed the ramp, saw Don and Isobel, and sat down on the edge beside them. He seemed to want to be friendly. "This will be something to tell your grandchildren about," he remarked. "Old Sir Ike at work. The best microtechnician in the system-can darn near pick out a single molecule, make it sit up and beg."

"It rather surprises me," Don admitted. "I hadn't known that Sir Isaac was a laboratory technician."

"He's more than that; he's a great physicist; hadn't the significance of his chosen name struck you?"

Don felt foolish He knew how dragons went about picking vocalized names, but he took such names for granted, just as he took his own Venerian name for granted. "His whole tribe tends to be scientific," Phipps went on. "There's a grandson who calls himself 'Galileo Galilei'; have you met him? And there's a `Doctor Einstein' and a `Madame Curie' and there's an integrating chemist who calls herself-Egg alone knows why!-'Little Buttercup.' But old Sir Ike is the boss man, the top brain-he made a trip to Earth to help with some of the work on this project. But you knew that, didn't you?"

Donald admitted that he had not known why Sir Isaac was on Earth. Isobel put in, "Mr. Phipps, if Sir Isaac was working on this on Earth, why doesn't he know what is in the ring before he opens it?"

"Well, he does and he doesn't. He worked on the theoretical end. But what we will find-unless we get a terrific disappointment-will be detailed engineering instructions worked out for man-type tools and techniques. Very different."

Don thought about it. "Engineering" and "science" were more or less lumped together in his mind; he lacked the training to appreciate the enormous. difference. He changed the subject. "You are a laboratory man yourself, Mr. Phipps?"

"Me? Heavens, no! My fingers are all thumbs. The dynamics of history is my game. Theoretical once-applied now. Well, that's a dry hole." His eyes were on the tank; the solvent, sluiced in by what seemed to be hogshead amounts, had washed the enamel out of the groove that defined that part of the initial "H"; the floor of the groove could be seen, bare, amber, and transparent.

Phipps stood up. "I can't sit still-I get nervous. Excuse me, please." .

"Surely."

A dragon was lumbering up the ramp. He stopped by them just as Phipps was turning away. "Howdy, Mr. Phipps. Mind if I park here?"

"Not at all. Know these people?"

"I've met the lady."

Don acknowledged the introduction, giving both his names and receiving those of the dragon in turn-Refreshing Rain and Josephus ("Just call me `Joe' "). Joe was the first dragon, other than Sir Isaac, whom Don had met there who was voder trained and equipped; Don looked at him with interest. One thing was certain: Joe had learned English from some master other than the nameless Cockney who had taught Sir Isaac... a Texan, Don felt quite sure.