Detective Inspector Carn of Scotland Yard, temporary medico, was not far from being typical of the modern C.I.D. man — the difference, in fact, being little more than an extra gramme or two of brain which lifted him a finger's breadth above the common competent herd and which had led to his being detailed for the special work of tracking the Tiger.

In other words, Carn was not obtrusively brilliant. He knew his job from A to Z, plus one or two other letters. He was a plodder, but an efficient plodder, having been taught in a school which prefers perseverance to genius and which trains men to rely on methodical painstaking investigation rather than on flashes of inspiration. Carn would never send an adoring gallery into rhapsodies with some dazzling feat of Holmesian deduction; he never whirled through a case in a kind of triumphant procession, with bouquets and confetti flying through the air, streamers blazing, and a brass band urging the awestricken populace to see the conquering hero come — but his superiors (a hard-headed and unromantic crowd) knew that he had a record of generally getting there, even if his progress and arrival were monotonous and unspectacular.

This brief biographical note is made for the disillusionment of anyone who has imagined that Carn was a genial cipher in the affair of the Tiger. He was not. But his tactics were different from those of the Saint, who had a weakness for the limelight and no reason to deny himself the gratification of his vanity. The Saint was one man, nearly as far outside the law as the Tiger, and therefore the Tiger would not hesitate to accept the challenge. But Carn represented Authority, a vast and inexorable machinery backed up by arms and men, and if Carn showed up in his true colours they were the colours of Authority — and before that the Tiger would hesitate for a long time. Carn had no chance of accomplishing his mission unless he worked underground and in the dark, and that, in a way, was a handicap, though it suited his temperament. But Carn, the stolid man hunter, took one look at the handicap, shrugged, and went on with the job — in his own laborious fashion.

The arrival of Mr. Templar, heralded by the Saint himself with the moral equivalent of a fanfare of terrific trumpets, illuminated with Kleig arcs, and fully equipped with one-man orchestra, noises off, self-starter, alarms, excursions, and all modern conveniences, lacking nothing but the camera men and press agent, had eclipsed Carn's modest efficiency, and perhaps had even put him off his plodding stroke for a while. But it would have taken more than a legion of Saints to derange our Mr, Carn permanently.

Carn was slow and Simon was sensational; but in the end they cancelled out, for Carn had had a start of several months. He knew from certain happenings one evening that Templar was hot on the Tiger's heels; he was not unduly perturbed, for he could have said the same for himself. In his quiet way, he had already given some attention to Sir John Bittle, and he knew quite a lot about that unpopular man and his strongly fortified house with its garrison of toughs. He had also put some work into Bloem, among others; but Bloem was the more slippery customer, and Carn had made very little headway, so that the Boer's sudden prominence in the field came as a surprise. Carn, recuperating from the shock with his well-tried resilience, had nevertheless not yet had time to follow up the clue which the Saint had provided. Carn had also an eye to the possibilities of Agatha Girton; he knew of her strange and secretive association with Bittle, but so far he had been unable to account for it better than by assuming her to be in with the gang — though in what capacity, and with what rank, he hadn't an inkling. There was Algy, for another; and Inspector Carn was prepared to believe startling things of Algy. The other three — Shaw, Smith, and Lapping — Carn had decided to rule out. Lapping in particular, with the policeman's ingrained reverence for the Law and its higher officers, he barred completely. In fact, except the Saint, Sir Michael Lapping was the only man in Baycombe who knew Carn's true designation and sole interest in life — Lapping was a Justice of the Peace, and Carn, hopeful of success, realized that the ex-judge was an indispensable ally, for Carn carried a warrant ready for Lapping's signature as soon as the name of the Tiger could be filled in with reasonable certainty. Taking things all round, therefore. Carn reckoned that he was as well posted as the Saint — and in this he was very nearly right. It was Carn's misfortune that he had never been privileged to make the acquaintance of Fernando, and that because of this loss he had been unaware of the significance of the Old House.

Carn had a hobby which he had only adopted since his arrival in Baycombe. He was as enthusiastic about it as he was about butterflies and beetles, but he reserved his pleasure for the hours when he was alone. The nearest telephone was at Ilfracombe, and by Carn's orders all letters addressed to Baycombe were opened at the post office there, copied, tested for invisible ink, and forwarded to their destinations after he had been informed of the results of this prying. It was because of divers hints which he had picked up by this means that Carn became so passionately devoted to wireless.

It was on the day following the apotheosis of Bloem, when the remains of his lunch had been cleared away, that Carn'shobby justified its adoption.

As soon as he found himself alone, the detective went over and unlocked his small roll-top writing desk. When this was opened, it revealed an ebonite panel arrayed with the complicated system of knobs, coils, and valves which have now ceased to be regarded as mysteries sealed from all but the scientist. The aerial Carn had fixed for himself among the rafters in the roof; and all the essential wiring was cunningly concealed. There was need of this secrecy, for Carn, who had never served an apprenticeship to a cook while walking his beat, was forced to employ a woman from the village to look after his digestion. Village women talk — and the nearest whisper that there was another radio fan in Baycombe, coming to the ears of the Tiger, would have deprived Carn of one of his most promising lines of investigation.

The detective put on the headphones, plugged in, and began his systematic combing of the ether. It was not easy for Carn to use his weapon even when he was convinced of its utility. He never knew at what time the Tiger might have arranged to communicate with his agent; though he did know the discouraging fact that the Tiger always called on a different wavelength. Twice Carn had struck the tail-end of a conversation, and had noted the dialling of his instrument, but the most patient listening had failed to pick up a second message; then, feeling round again. Carn had caught the same signal in a totally different range. Probably the wavelength changed according to a prearranged timetable.

This, however, was Carn’s lucky day. The Tiger was using a very long wave, and Carn had reversed his usual routine and started at the top to work down the scale. He had not been probing the atmosphere for five minutes before he tuned in on a peculiar high-pitched tremulous whine which he recognized immediately for the note sent out by the Tigers apparatus in the gaps when no speech was coming over. And he had hardly brought the last condenser round to the exact reaction, so that the familiar note was singing in his ears at full strength, when a voice cut clean across the humming.

"Don't start to come in before it's quite dark."

Carn stiffened. He had some idea of what was referred to.

The voice continued: "Be very careful. See that there isn't a light showing anywhere, and slow up to half speed when you're two miles out. Change over to the electric motors at that point — Templar stays awake at4iight,and his hearing's exceptionally good."