RUNNING DOWN A CLUE.

Chub McReady had no very clear idea why Carl was displaying so much hostility toward Slocum. The bell-boy had mentioned Slocum's name in connection with carrying the pitcher of water to Matt's room, and Chub supposed Carl was to do some questioning along that line. The drawing of the revolver not only surprised Chub, but led him to believe that Slocum had a guilty conscience and was ready to go any length in defending himself.

"This is an infernal outrage, by gad!" cried Slocum. "What do you young ruffians mean by setting upon me like that?"

As he spoke he picked up a newspaper and threw it over the table. It was an odd move for a man to make at such a time.

"Vat do you mean py making some moofs mit a gun?" demanded Carl.

"Why, you pie-faced Dutchman, why shouldn't I pull a gun when I'm set upon like that? I was just leaving my room to go down to breakfast when you began to climb all over me. What's the matter with you, anyhow?"

"Pie-face!" gasped Carl; "you call me dot! Py chincher, you haf got a face like some hedge fences, und you haf a heart vat iss so plack und dricky as I can't dell. Vat you do ven you meed der poy pringing some vater py Modor Matt's room lasdt nighdt? Tell me dot!"

"Do? I sent him down to see if there was any mail for me. What business is that of yours, anyway? Give me that gun and get out of here, both of you!"

Slocum gave the paper another hitch on the table. Chub was already guessing about the moves he had made with that paper, and what he saw now brought his guessing to the suspecting stage. Stepping to the table, he cast the paper aside. A small bottle, half-full of some drug, lay on the table. Slocum, with a quick sweep of his hand grabbed the bottle away.

"He's got somet'ing he don'd vant us to see!" exclaimed Carl.

"I'm next to that, all right," said Chub. "Put it back on the table, Slocum," he added sharply. "Don't be a mutt. I'm from Arizona, and we don't speak twice when we back up our first talk with a gun."

"This is my property!" faltered Slocum, peering shiftily into Chub's steady eyes.

"You're so blamed careful of it that I'd about made up my mind it belonged to you. Anyhow, drop it on the table. Last call!"

Slocum laid the bottle down.

"By gad," he blustered, "somebody'll pay for this!"

"Look out it ain't you," grinned Chub. "Pick it up, Carl, and we'll take it down to the office, where we can look it over."

"Take that away from here," fumed Slocum, "and I'll——"

As Carl picked up the bottle Slocum made a grab at him.

"Steady!" warned Chub. "Now duck, Carl. We've found out all we can in this place."

With the bottle in his hand Carl walked out of the room. Chub backed out. Taking the key out of the door, he dropped the revolver on the carpet, jumped into the hall, slammed the door and locked it on the outside.

"That's to give him a chance to get over his mad spell before he tried to shoot," Chub grinned as he rejoined Carl and they took their way down-stairs.

"You don'd know aboudt dot feller und Matt," said Carl, "und I vill dell you. Den you vill know vat I know und ve can guess oudt der resdt togedder."

They went out on the porch and took a couple of chairs; then Carl told how Slocum had called on Matt, in Denver, claimed he was Colonel Plympton and, by trickery, got him to sign a paper that had lost him the opportunity of driving a car for the Stark-Frisbie Company.

Chub scowled.

"I sized him up for bein' pretty low-down," said he, "but I hadn't any notion he'd pull off a trick like that. What did he do it for?"

Carl went on with an account of the doings of Sercomb and his gang. Chub's wrath had been mounting by swift degrees.

"That's a fine lay-out!" he growled savagely. "The gang has done something to Matt, that's a cinch. But what? Matt goes off by himself, bag and baggage, at midnight, looking like he was locoed. Queerest thing I ever heard of!"

Before Carl could make any comment, Mr. Trueman came up the porch steps and started toward him.

"Matt was to meet me at the garage this morning at eight o'clock," said he, "and we were to talk over some important matters. Why didn't he come, Carl?"

"Dot's vat ve don'd know, Misder Drooman," answered Carl gloomily. "Modor Matt don'd been aroundt der hodel since mitnighdt."

Trueman stood as though stunned.

"Matt hasn't been at the hotel since midnight?" he repeated blankly.

"Dot's vat's der madder. Dere has peen some keveer pitzness going on in dis blace, you bed my life, und vere Matt iss ve don'd know."

Trueman drew a handkerchief from his pocket and passed it across his face; then he dropped into a chair.

"If anything has happened to King, now," said he, "it will be pretty nearly the last straw. Tell me all about this thing—give me the whole of it, and be as quick as you can."

Between them Carl and Chub contrived to give Trueman a fairly lucid idea of what they had done and what they had discovered.

Trueman, an ominous frown on his face, took the bottle which Carl had brought away from Slocum's room. The label contained but the two words, "Cannibis indica."

"It's a drug of some sort," he muttered, holding the bottle up between his eyes and the light and shaking it. "Matt has told me all about Slocum's double dealing, and how the fellow is working with Sercomb and his gang. Do you suppose Slocum merely sent the bellboy down after the mail for a bluff?"

"Bluff!" echoed Chub. "What kind of a bluff?"

"Why, so he'd be alone with the pitcher of water long enough to empty some of the contents of this bottle into it."

Carl and Chub were astounded.

"Dot's vat he dit, und I bed you anyt'ing vat I got!" cried Carl.

"He doped Matt's drinking-water," averred Chub, "and that's the straight of it. I move we go upstairs and lay the tin-horn by the heels. If he's doing that sort of business he ought to be in the calaboose."

"We'll go up and have a talk with him," said Trueman. "Unless he can give a good explanation of what this bottle of stuff is for, we'll walk him over to the jail and land him behind the bars."

A hurried trip was made to the second floor, but Trueman and the boys were too late. Slocum had got someone to open the door for him and he was gone.

"Ach, plazes!" said Carl angrily; "ve ought to haf pud some ropes on him so dot he couldn't ged avay. Dot's vere ve vas lame, Chub. Now how ve going to findt oudt vere iss Modor Matt?"

"Slocum, guilty or innocent, wouldn't be able to help us find Matt," spoke up Trueman. "The thing for us to do is to hunt up a doctor and find out just what effect this cannibis indica has on a person. It may be that we're on the wrong track entirely."

There was a doctor in the office building next the hotel. His name was Davis. He was an old doctor, but a knowing one.

"Cannibis indica," said he, "is a drug that has a very powerful effect upon the brain. It is not dangerous if taken in a small amount. A small dose of it would not induce a state of lethargy, but would be more apt to unhinge a person's mind and cause him to do things of which he would have no remembrance when the effect wore away."

"How long would the effect last?" asked Trueman anxiously.

"That would depend altogether upon the amount that was taken. In this case, two or three days, perhaps."

When Trueman and the boys left the doctor's office the mystery was cleared as to the cause of Matt's sudden departure, but was as deep as ever concerning his present whereabouts.

"For several days," said Trueman, "Matt's enemies have held back. I suppose they planned this thing so as to work it at just the right time to keep Matt out of the race. If he doesn't get back here before long I'll raise Cain with the scoundrels who had a hand in the work. I'm going to see the authorities and have them telegraph and telephone to the surrounding towns. While I'm busy about that, you boys return to the hotel, get a duplicate key of the room, and take the pitcher of water you find there over to Dr. Davis. Ask him to find out if any of the cannibis indica was mixed with it. I'm fairly positive as to what his answer will be, but this is a case where we've got to be sure of every step."

By noon the telegraph and telephone had carried their alarm into the neighboring country. The town was being searched, not only for Matt, but also for Slocum. Dr. Davis had declared that the water in the pitcher had contained a strong solution of the drug. Circumstantial evidence connected Slocum with the administering of the drug so that there was not the least shadow of a doubt.

But Slocum could not be located; and neither could Matt. An afternoon of miserable anxiety passed for Carl and Chub, to be followed by a no less miserable and uneventful night.

Monday, the day before the great race, came, bringing crowds of people by every train—but Motor Matt was not among them.

Carl, as Chub expressed it, had "gone off the jump" entirely; and Chub himself was not much better off.

Trueman, grimly resenting what had happened to his driver, was firmly determined, if Matt did not present himself before the race was started, to arrest every one of the Stark-Frisbie drivers.

If the Jarrot car was to be kept out of the race for lack of a driver, Trueman would see to it that some of the other cars were left in like condition. In levelling their contemptible plot against Motor Matt, the guilty drivers would find that they had launched a boomerang.

This was the condition of affairs up to midnight, Monday night, and the first of the racers was to be started at eight sharp, Tuesday morning.