Reluctantly, he shot up to the surface for air. This was easy; he felt ashamed of his previous fears. Now he understood how visitors often reacted to Titan. Next time, when someone politely declined an invitation to take a pleasant jaunt outside, he would be a little more tolerant.

“What are those black things?” be asked Dr. Todd, who was still hovering watchfully above him.

“Long-spined sea urchin, Diadema something-or other When you see so many, it’s a sign of pollution or an unbalanced ecology. They don’t really damage the reef-unlike Acanthaster-but they’re ugly, and a nuisance. If you back into one, the needles may take a month to work their way out. Are you going down again?”

“Yes. 99

“Good. Don’t overdo it. And watch out for those spines!”

Duncan hauled himself down the anchor line once more, and the diver waved him a greeting as he approached. Then she offered him her deadly-looking knife, and pointed toward a small group of sea urchins. Duncan nodded, took the tapering metal blade by the proffered handle, and started jabbing away inexpertly, being careful to avoid those ominous black needles.

Not until then did he realize, to his considerable surprise, that these lowly animals were aware of his presence, and were not relying merely on a static defense. The long spines were swinging toward him, orienting themselves in the direction of maximum danger. Presumably it was only a simple automatic reflex, but it made him pause for a moment. There was more here than met the eye-perhaps the first faint intimations of dawning consciousness.

His knife was longer than the sea urchin’s spines, and he jabbed

vigorously again and again. The cara216 pace was surprisingly tough, but presently it gave way, and the waiting fish raced in to grab at the creamy white flesh that was suddenly exposed.

And then, with growing discomfort, Duncan realized that his victim was not dying in silence. For some time he had been aware of faint sounds in the water around him-the hammering of the other divers on the reef, the occasional “clang” of the anchor against the rocks. But this noise came from much closer at hand, and was most peculiar-even disturbing. It was a crackling, grinding sound; though the analogy was patently ridiculous, it could only be compared to the crunching of thousands of tiny teeth, clashing in rage and agony. Moreover, there was no doubt that it came from the eviscerated sea urchin.

That faint, inhuman death rattle was so unexpected that Duncan checked his onslauLyht and remained howe ring motionless in the water. He had completely forgotten the necessity for air, and the conscious part of his mind had dismissed the mounting symptoms of suffocation as irrelevant-to be dealt with later. But finally he could ignore them no longer, and shot gasping to the surface.

With a profound sense of shock-even of shame Duncan realized that he had just destroyed a living creature. He could never have imagined, before he left Titan, that such an experience would ever come his way.

One could hardly feel much guilt over the murder of a sea urchin.

Nevertheless, for the first time in his life, Duncan Makenzie was a

killer.

SLEUTH

When Duncan returned to Washington, the second time bomb from Colin was ticking away in the Centennial Hotel. Once again, it was so cryptic that it would have been almost unintelligible, even to an outsider who had succeeded in decoding it.

CONFIRM YOUR OLD FRIEND HAS UNAUTHORIZED ACCOUNT 65842 GENEVA BRANCH

FIRST

BANK OF ARISTARCHUS. BALANCE SEVERAL TENS OF THOUSANDS SO LARS THIS

INFORMATION NOT TO BE DISCLOSED ANY CIRCUMSTANCES. PRESUME FROM SALE

OF

TITANITE. MAKING INQUIRIES MNEMOSYNE. MEANWHILE SUGGEST YOU KEEP

ALERT.

REGARDS COLIN.

Duncan understood perfectly well why this information was “not to be disclosed”; the Lunar banks guarded their secrets well, and heaven alone knew by what prodigies of persuasion or genteel blackmail Colin had managed to get hold of Karl’s account number. Even so, he had been unable to obtain a figure for the balance-but it was obviously considerable. Ten thousand so lars was far more than anyone would need for the purchase of a few Terran luxuries. And several times that was more than the Makenzies held in their own, perfectly legal accounts. Such an amount of money was more than a cause for envy; it was disturbing, especially if it was intended for some clandestine use.

Duncan allowed himself a few moments of wistful daydreaming, imagining what he could do with twenty or thirty thousand so lars Then be put

the seductive vision firmly aside and concentrated all his mind upon the problem. While Karl’s involvement had been only a vague suspicion, he had been reluctant to waste time on a detailed analysis of how, when, and-above all -why. But now that speculation had congealed into certainty, he could no longer evade the issue.

What a pity that the obvious line of approach was out of the question! He could hardly call up the First Bank of Aristarchus and ask for a print-out of Account 65842. Not even the World Government could do that, unless fraud or crime had already been proved beyond a shadow of a doubt. Even the most discreet inquiry would trigger an explosion; someone would certainly be fired, and Colin might be faced with most embarrassing questions.

The only real problem in life, an ancient philosopher had once said, is what to do next. There was still no link with Calindy-or anyone else.

Duncan did not relish playing a role in some sleazy, old-time spy or detective melodrama, and was not even sure how one got started on such an enterprise. Colin would have been much better at it; of the three

Makenzies, he was the only one with any flair for subterfufe. indirection, and secrecy. He was probably enjoying himself-especially since he had never liked Karl, being one of the few people on Titan immune to his charms.

But Colin, though he was do ini g a remarkable job, was more than a billion kilometers away, at the end of an expensive three-hour time-lag.

There was no one on Earth in whom Duncan could confide.

This was a private Titanian matter, and might yet turn out to be a storm in a teacup. However, if it was serious, the fewer people who knew about it, the better.

Duncan considered, and dismissed, the idea of talking to Ambassador

Farrell. He might have to enter the picture later, but not now. Duncan had not been too impressed with Bob Farrell’s discretion-and, of course, he was a Terran. Moreover, if the Embassy discovered that there was a large amount of master less money floating around Earth, that would undoubtedly precipitate a tug-of-war. It was true that the rent on Wyoming Avenue had to be paid, but Titan’s demands were even more urgent.

A,nd yet perhaps there was one Terran he could trust-the man who had raised the matter in the first place, and who was equally interested in finding the answer. Duncan tapped out the name on his

Comsole, wondering if it would accept that ridiculous apostrophe. (He had managed to misplace the dealer’s card, which would have placed the call automatically.)

“Mr. Mandel’stahm?” he said, when the screen ]it up. “Duncan Makenzie. I have some news for you. Where can we meet for a private conversation?”

“Are you absolutely certain,” said Duncan anxiously, “that no one can overhear us?”

“You’ve been seeing too many historical films, Mr. Makenzie,” Ivor

Mandel’stahm replied. “This isn’t the twentieth century, and it would take a singularly determined police state to bug every auto jitney in Washington.

I always do my confidential business cruising round and round the Mall.

There’s absolutely nothing to worry about.”

“Very well. It’s imperative that this doesn’t go any further. I am fairly sure that I know the source of the titanite. What’s more, I have a very good idea of the Terran agent-who has apparently already made some substantial sales.”