What would have been invisible to such a watcher was the thin, telescopic antenna projecting beyond the barrel of the device. For Mark was in fact engaged with April Dancer on a remote-control check of Sheila Duncan's booth at the circus.

After some argument and haggling, the girl had succeeded in persuading the older Bosustow to let her take over the souvenir kiosk temporarily, and now, just after the afternoon opening of the sideshows, she was busy checking the stock. Since she was not supposed to know Mark, and since the booth was too small to conceal anybody, they had decided to maintain radio contact while she was actually there rather than compare notes in secret some time later in the day. "It's really more practical that way," April had argued. "Always better to discuss things as they come up than to try and recall every detail afterwards. And since I can't hide you inside, and you won't have any excuse for lounging about outside because you don't know me, I think our U.N.C.L.E. Communicators are the answer, don't you?" Slate had agreed, stipulating only that his end of the operation should be out in the country rather than in the town, where his actions might be noticed visually, or in his hotel room, where he might be overheard. He listened now to April's description of what she had found on the shelves and in the cupboards of the tiny booth.

"She had stuff in Serpentine, Onyx, Porphyry, Agate and Chrysopase, as far as I can see," she said; "the great majority of it being Serpentine. And it's fairly obvious, both from the books, such as they are, and from the stock, that lighthouses in Serpentine are the best sellers — in all sizes, from a couple of inches high to almost a foot. Next on the list are ashtrays — in the green Serpentine, the red, and in Moss Agate. And after that come various kinds of creatures, Cornish pixies mostly."

"What are they made of?" Mark asked curiously, raising the Communicator to his lips after a cautious glance around.

"Chrysoprase and Onyx, chiefly the former. They're pretty stylised, mind you, with very little detail: none of those minerals lend themselves to the kind of sentimental work that pixies normally demand. And in any case they are not suitable for mass production techniques — even the kind where each item is made separately!"

"Tell me one thing," Mark queried. "What the devil is Chrysopase?"

The voice percolating through the tiny Communicator in his hand sounded amused. "It's a green variety of Chalcedony — which, as I'm sure you must know, is a kind of semi-precious quartz... Apart from these, there are eggcups and small vases in Serpentine, trinket boxes in Serpentine and Agate, and paperweights — very classical in style — made in everything. May I keep you something, sir?"

"What are the pixies like?"

"They look as though they had leprosy."

"Oh. Perhaps I'd better —"

"Hold it Mark," April's voice interrupted. "I have customers. This is the third today. Business is booming! I shall leave the Communicator on so you can hear — but don't for goodness' sake say anything."

He heard a Cornishwoman's voice saying something indistinct. And then April, very clearly: "Yes, they are pretty, aren't they, dear?... No, the big ones are rather expensive, I'm afraid... Three pounds ten... Yes, of course, I understand... These small ashtrays are nice for a casual present; come in handy at any time. And they're only twelve and six. Just as you like... Yes, you do that…"

"No sale, I gather," he said when the girl came on the line again.

"No. I didn't really — Oh. Hold on again. There's this youth has been hanging about for some time: Now he's coming over. Can't say I like the look of him much. Keep quiet... Good afternoon, sir. Can I help?"

This time, the voice was clear and well-defined. A Londoner, or at any rate from the Home Counties, Slate thought. Not too well educated, but self-confident, almost cocky.

"Hullo, love. I'd like a Cornish pixie, please. In black Porphyry."

"In black...? A pixie? Just a moment, I don't think... Will you hold on a minute, sir. I'll just have a look."

Over the diminutive transmitter, Slate heard the sound of whistling overlaid by the opening and shutting of drawers and cupboard doors. And then the girl's voice, puzzled: "I'm so sorry, sir. I'm afraid we don't have any pixies in Porphyry, black or otherwise. Can I interest you in—"

"No, it's a pixie, in black Porphyry," the boy cut in.

"Well, I'm terribly sorry... We do have Porphyry ashtrays. Black and red, as you see. And stud boxes."

"Are you sure you don't have black Porphyry pixies?"

"Well, yes. I've just told you, haven't I?"

There was a short silence, and then the youth's voice mumbling: "Okay, okay. Have it your way. You don't have any. But they definitely said..." The voice died away as he walked out of range of the set.

"That was odd," April's voice said a few minutes later. "Look — there's a big cupboard full of odds and ends at the back of the booth. I think I'll sort through that in the next few minutes. There may be notebooks, papers, or at any rate something of interest to us there.. though if Miss Duncan had been as thoroughly trained as we have to be, I doubt it very much!"

"Okay," Mark replied. "You do that. While you're making a start, I shall take off and move the car somewhere else. I don't want to stay too long in any one place, in case people start noticing. As it is, half the wretched population down here seem to have field glasses!"

He drove back into the town and out along the track skirting the harbour and the bathing beach. On top of the headland separating Porthallow from the adjoining cove, he pulled off the road and stopped the car in a grassy depression. Beyond the clifftop, the white shapes of gulls floated in an up-current of air against the haze merging sea and sky in the winter sun. After he had switched off the engine, he listened to the booming of surf somewhere out of sight below and then drew the Communicator from his pocket and touched the button which would actuate the call-sign bleep on the twin that April had.

"Channel open," the girl's voice came crisply from the tiny speaker.

"Slate. I'm up on the cliffs on the other side of the town."

"Good. I've been busy too. I've sold a small round stud box in Agate since you called, and two lighthouses. Only the smallest, mind, but it's a start, don't you think?"

"Most commendable," Mark said dryly.

"And there's another funny thing too. Remember you heard the boy who asked for a black Porphyry pixie? Well, someone else came up and asked had I one."

"That is odd. Who was it? Did they ask in the same words?"

"A spotty young man of about twenty-two, I should judge. He didn't ask right out. Just wanted to see things in black Porphyry. And when it turned out that there were no pixies, he lost interest and went away."

"So what's so special about pixies in black Porphyry, one wonders? You have checked? There really are none?"

"Yes and no. Respectively."

"April — you don't think this is... a sign?... do you?"

"Like From Above, you mean? Or like an omen, a pointer?"

"Something like a word to the wise."

"Well, of course it did strike me, after the second request, that it might be some kind of coded intro. But what for, I can't think."

"If there were black Porphyry pixies available only to those who asked for them, but not on display, then it might make some kind of sense. But since you say there definitely are none —"