Out with it! Where did you meet 'em and where did you drive 'em?"

Realizing that escape was cut off and thoroughly cowed by the display of force, Murphy told the whole story--or as much of it as he knew.

"I was drivin' down Broadway round Twenty-eig't Street last night, 'bout ten o'clock," he confessed. "I'd taken that couple to the the-ayter, just as I told you, an' that man up to Harlem. Then one of these t'ree guys hailed me...."

"Three?" interrupted Whitney.

"That's what I said--t'ree! They said they wanted to borrow my machine until six o'clock in th' mornin' an' would give me two hunnerd dollars for it. I told 'em there was nothin' doin' an' they offered me two-fifty, swearin' that they'd have it back at th' same corner at six o'clock sharp. Two hunnerd an' fifty bones being a whole lot more than I could make in a night, I gambled with 'em an' let 'em have th' machine, makin' sure that I got the coin foist. They drove off, two of 'em inside, an' I put in th' rest of th' night shootin' pool. When I got to th' corner of Twenty-eig't at six o'clock this mornin', there wasn't any sign of 'em--but th' car was there, still hot from the hard ride they give her. That's all I know--'shelp me Gawd!"

"Did the men have any bags with them?"

"Bags? No, not one."

"What did they look like?"

"The one that talked with me was 'bout my heig't an' dressed in a dark suit. He an' th' others had their hats pulled down over their eyes, so's I couldn't see their faces."

"Did he talk with a German accent?"

"He sure did. I couldn't hardly make out what he was sayin'. But his money talked plain enough."

"Yes, and it's very likely to talk loud enough to send you to the pen if you're not careful!" was Whitney's reply. "If you don't want to land there, keep your mouth shut about this. D'you get me?"

"I do, boss, I do."

"And you've told me all the truth--every bit of it?"

"Every little bit."

"All right. Clear out!"

When Murphy left the room, Whitney turned to the manager and, with a wry smile, remarked: "Well, we've discovered where the car came from and how they got it. But that's all. We're really as much in the dark as before."

"No," replied the manager, musingly. "Not quite as much. Possibly you don't know it, but we have a device on every car that leaves this garage to take care of just such cases as this--to prevent drivers from running their machines all over town without pulling down the lever and then holding out the fares on us. Just a minute and I'll show you.

"Joe," he called, "bring me the record tape of Murphy's machine for last night and hold his car till you hear from me."

"This tape," he explained, a few minutes later, "is operated something along the lines of a seismograph or any other instrument for detecting change in direction. An inked needle marks these straight lines and curves all the time the machine is moving, and when it is standing still it oscillates slightly. By glancing at these tapes we can tell when any chauffeur is holding out on us, for it forms a clear record--not only of the distance the machine has traveled, but of the route it followed."

"Doesn't the speedometer give you the distance?" asked Whitney.

"Theoretically, yes. But it's a very simple matter to disconnect a speedometer, while this record is kept in a locked box and not one driver in ten even knows it's there. Now, let's see what Murphy's record tape tells us....

"Yes, here's the trip to the theater around eight-thirty. See the sharp turn from Fifth Avenue into Forty-second Street, the momentary stop in front of the Amsterdam, and the complete sweep as he turned around to get back to Broadway. Then there's the journey up to the Bronx or Harlem or wherever he went, another complete turn and an uninterrupted trip back down on Broadway."

"Then this," cut in Whitney, unable to keep the excitement out of his voice, "is where he stopped to speak to the Germans?"

"Precisely," agreed the other, "and, as you'll note, that stop was evidently longer than either of the other two. They paid their fares, while Murphy's friends had to be relieved of two hundred and fifty dollars."

"From there on is what I'm interested in," announced Whitney. "What does the tape say?"

"It doesn't _say_ anything," admitted the manager, with a smile. "But it _indicates_ a whole lot. In fact, it blazes a blood-red trail that you ought to be able to follow with very little difficulty. See, when the machine started it kept on down Broadway--in fact, there's no sign of a turn for several blocks."

"How many?"

"That we can't tell--now. But we can figure it up very accurately later.

The machine then turned to the right and went west for a short distance only--stopped for a few moments--and then went on, evidently toward the ferry, for here's a delay to get on board, here's a wavy line evidently made by the motion of the boat when the hand ought to have been practically at rest, and here's where they picked up the trip to Trenton. Evidently they didn't have to stop until they got there, because we have yards of tape before we reach a stop point, and then the paper is worn completely through by the action of the needle in oscillating, indicative of a long period of inaction. The return trip is just as plain."

"But," Whitney objected, "the whole thing hinges on where they went before going to Trenton. Murphy said they didn't have any bags, so they must have gone home or to some rendezvous to collect them. How are we going to find the corner where the machine turned?"

"By taking Murphy's car and driving it very carefully south on Broadway until the tape indicates precisely the distance marked on this one--the place where the turn was made. Then, driving down that street, the second distance shown on the tape will give you approximately the house you're looking for!"

"Good Lord," exclaimed Whitney, "that's applying science to it! Sherlock Holmes wasn't so smart, after all!"

Al and the manager agreed that there was too much traffic on Broadway in the daytime or early evening to attempt the experiment, but shortly after midnight, belated pedestrians might have wondered why a Green-and-White taxicab containing two men proceeded down Broadway at a snail's pace, while every now and then it stopped and one of the men got out to examine something inside.

"I think this is the corner," whispered the garage manager to Whitney, when they reached Eighth Street, "but to be sure, we'll go back and try it over again, driving at a normal pace. It's lucky that this is a new instrument and therefore very accurate."

The second trial produced the same result as the first--the place they sought lay a few blocks west of Broadway, on Eighth.

Before they tried to find out the precise location of the house, Whitney phoned to headquarters and requested loan of a score of men to a.s.sist him in the contemplated raid.

"Tell 'em to have their guns handy," he ordered, "because we may have to surround the block and search every house."

But the taxi tape rendered that unnecessary. It indicated any one of three adjoining houses on the north side of the street, because, as the manager pointed out, the machine had not turned round again until it struck a north-and-south thoroughfare, hence the houses must be on the north side.

By this time the reserves were on hand and, upon instructions from Whitney, spread out in a fan-shaped formation, completely surrounding the houses, front and rear. At a blast from a police whistle they mounted the steps and, not waiting for the doors to be opened, went through them shoulders first.

It was Whitney, who had elected to a.s.sist in the search of the center house, who captured his prey in a third-floor bedroom.

Before the Germans knew what was happening Al was in the room, his flashlight playing over the floor and table in a hasty search for incriminating evidence. It didn't take long to find it, either. In one corner, only partly concealed by a newspaper whose flaring headlines referred to the explosion of the night before, was a collection of bombs which, according to later expert testimony was sufficient to blow a good-sized hole in the city of New York.

That was all they discovered at the time, but a judicious use of the third degree--coupled with promises of leniency--induced one of the prisoners to loosen up the next day and he told the whole story--precisely as the taxi tape and Vera Norton had told it. The only missing ingredient was the power behind the plot--the mysterious "No.

859"--whom d.i.c.k Walters later captured because of the clue on Shelf forty-five.

"So you see," commented Quinn as he finished, "the younger Pitt wasn't so far wrong when he cynically remarked that 'there is a Providence that watches over children, imbeciles, and the United States.' In this case the princ.i.p.al clues were a book from the Public Library, the chance observations of a girl who couldn't sleep and a piece of white paper with some red markings on it.

"At that, though, it's not the first time that German agents have gotten into trouble over a sc.r.a.p of paper."

"What happened to Vera Norton?" I inquired.

"Beyond a little personal glory, not a thing in the world," replied Quinn. "Didn't I tell you that Al was married? You're always looking for romance, even in everyday life. Besides, if he had been a bachelor, Whitney was too busy trying to round up the other loose ends of the Ewald case. 'Number eight fifty-nine' hadn't been captured then, you remember.

"Give me a match--my pipe's gone out. No, I can't smoke it here; it's too late. But speaking of small clues that lead to big things, some day soon I'll tell you the story of how a match--one just like this, for all I know--led to the uncovering of one of the most difficult smuggling cases that the Customs Service ever tried to solve."