"Yes," replied the a.s.sistant. "Of course I opened it for the delivery men; but I bolted it as soon as they had gone. Then, today, when they brought the guinea pigs -"

"The guinea pigs?"

"Yes, sir. The same men. They came back with a crate of guinea pigs. They said they had been mistaken about the shipments. The equipment was for another laboratory. The guinea pigs were consigned to you."

"I ordered no guinea pigs."

"No?" Benzig looked surprised. "There were only a few left, sir! I thought of course this second consignment must be a correct one."

"Where did you put the guinea pigs?"

"In your private laboratory, sir, where you always keep them."

VALDAN stalked across the big room. He reached an inner door and opened it. He stepped into a small laboratory where a confused array of boxes was strewn on a table. Benzig followed his employer.He pointed to a crate of guinea pigs which lay in a corner at the right side of the room.

"Probably a duplicate a.s.signment," crackled Valdan, in a querulous tone. "What did you do with the few cavies that I still had here?"

"I put them in this crate with the new guinea pigs," replied Benzig. "I let the delivery men take the old box away with them."

Valdan nodded. He looked about the room while Benzig watched him. This small laboratory was a curious place. Its small amount of equipment was located in the center, directly opposite the door, at the spot where the box-strewn table stood.

There was a door to a closet at the left side of the room. At the right, just beyond the box of guinea pigs, the entire wall formed a huge file cabinet that went up to the ceiling. The drawers were marked with cards that listed numbers. A step-ladder was handy, as a means of reaching the higher files.

To Benzig, this small laboratory was a room of mystery. Like the outer door of the large laboratory, it was fitted with a bolt. Whenever Troxton Valdan used this room for experiments, he invariably entered and bolted the door behind him.

When Valdan was absent from the house, the door of the little laboratory remained unlocked, for it was fitted with bolt alone. On these occasions, Benzig was very careful about the outer door of the large laboratory, for it opened between this house and the next and might easily prove a lurking place for intruders bent on robbery.

Troxton Valdan registered annoyance as Benzig watched him. The gray-haired chemist seemed perplexed by these matters of delivery. When he spoke again, his tone was critical.

"I have confidence in you, Benzig," declared Valdan. "I chose you as an a.s.sistant chiefly because I was sure you would not pry into my private experiments."

"I have never done so," reminded Benzig.

"I am sure of that," agreed Valdan, "but I also had faith in your discretion, Benzig. I am disappointed.

You must be more careful in the future. You must not permit delivery men to prowl about these laboratories."

"I am sure that they touched nothing, sir -"

"How can you be sure? You admitted that you went upstairs to speak to Crowder."

"That was yesterday, sir. But today, I remained in the outer laboratory while the men brought the crate in here."

"Stupid of you! You should have came in here with them."

"But they were only in here long enough to leave the crate of guinea pigs. I entered as they were leaving.

That was when I transferred the extra guinea pigs and called the men back to take the old crate."

"That is sufficient." Valdan moved over toward the table. "Where is my afternoon newspaper, Benzig?"

"It should be on the table, sir. Crowder invariably brings it here."

"Did he do so today?" "I think so, Mr. Valdan."

"Think!" cackled the chemist, in an irritated tone. "If you did any real thinking, Benzig, you would know whether or not Crowder placed the journal here. I hired you as an a.s.sistant, Benzig, not as a dummy."

Valdan was rummaging among the boxes on the table. He uncovered one that was partly obscured by others. He raised the lid and peered inside. The box contained two guinea pigs. Both of the cavies were motionless. Valdan rapped at the side of the box, tapping with his fingers upon punctured air holes. The guinea pigs did not budge. Valdan replaced the cover of the box.

The chemist turned suddenly, expecting to see Benzig. The a.s.sistant was no longer in view. Valdan stared about suspiciously; then closed the door of the laboratory and shot the bolt. He stooped and peered below the table. There, an old piece of carpeting was draped over a wooden box. Valdan chuckled and began to rise. Then, to make sure, he stooped again and pulled away the old carpet.

A gasp came from the chemist's lips. Apparently, this was not the box that Valdan had expected to find.

He was puzzled by its shape and its appearance. The lid was nailed in place. Seizing a hammer that lay upon the table, Valdan pried away a board. He stared into the box. Its only contents were some short lengths of rusted iron pipe.

THE chemist scrambled to his feet. He stared wildly at the door that he had bolted; then looked toward the file cabinets at the end of the room. Hurrying in that direction, Valdan seized the little ladder and mounted to the highest step. With quivering hands, he pulled open a drawer that bore the numbers: 96-115.

Large folders filled the drawer. Valdan rummaged through them, muttering numbers half aloud. His voice became a hoa.r.s.e, anxious whisper: "One hundred and nine - one hundred and ten - one hundred eleven -"

The chemist stopped short. The number that he had just named was missing. He gripped an envelope that bore the number 110. The next one in the drawer was 112.

"Benzig!" The chemist blurted the name, in a wild call for his missing a.s.sistant. "Benzig!"

Valdan had forgotten that he had bolted the door. A slight sound from behind him made him think that his a.s.sistant had returned. Scrambling downward from the ladder, Valdan began to turn. A click from the door; the little laboratory, windowless, was plunged in darkness. A form sprang forward; Valdan grappled with an unseen a.s.sailant.

The struggle was short-lived. Valdan toppled to the floor. Hands gripped his head and pounded it fiercely upon the stone flooring. Fierce panting sounded in the darkness. Then the vicious a.s.sailant held his breath and listened. No further sound came from Troxton Valdan.

The killer arose. Though he tiptoed, his footfalls clicked strangely in that darkened room. Then came the grate of the bolt as Valdan's attacker drew it back. Eyes peered into the deserted outer laboratory. The killer moved forth and closed the door behind him.

Deep stillness reigned in the inner room. Minutes pa.s.sed; then the door opened and an astonished exclamation came in the voice of Benzig. The a.s.sistant seemed surprised to find the room in darkness.

"I - I thought Mr. Valdan was in here!" Benzig was speaking to Crowder, who had come with him. "But - but the light is out -" Crowder's hand pressed the switch. Then came blurted exclamations from both servant and a.s.sistant.

Standing just inside the doorway, they stared at the p.r.o.ne form of their employer. Troxton Valdan was lying face up on the floor, at the bottom of the ladder. His feet were beside the lowest step.

The chemist's head was resting in a pool of blood. His skull had been fractured by that smash against the floor. Crowder and Benzig staring, both had the same thought. The servant was the first to voice it, in an awed gasp.

"Dead!" whispered Crowder, tensely. "The master - Mr. Valdan - someone has killed him!"

CHAPTER VI. TWO GUINEA PIGS.

ONE hour after Crowder and Benzig had discovered the body of Troxton Valdan, Police Commissioner Wainwright Barth emerged from a telephone booth at the Cobalt Club. He hurried excitedly to the cloak room and thrust his head across the counter while he pointed out his coat and hat. He wanted the garments quickly.

Seizing his coat from the attendant, Barth began to put it on as he hastened toward the outer door. As he neared the exit, the commissioner b.u.mped into another person who was entering. Grasping his spectacles just as they were about to drop from his nose, Barth found himself face to face with Lamont Cranston.

"Sorry, commissioner," remarked the millionaire, in his quiet manner. "What is the trouble?"

"An important police case," responded Barth, pausing long enough to explain his haste. "A strange death that requires my personal investigation."

"You have your car here?"

"No. I intend to take a cab."

"Not at all. My limousine is outside. At your service, Mr. Barth."

Turning, Cranston accompanied the commissioner to the sidewalk. Stanley caught the door man's signal.

The limousine rolled over to the curb. Cranston motioned Stanley to remain at the wheel. While the Cobalt Club attendant was opening the door of the car, Cranston gave instructions.

"Drive Commissioner Barth wherever he orders," said Cranston, to Stanley. "Keep the car at his disposal. Simply telephone me, Stanley, so that I shall know where to reach you."

"This is fine of you, Cranston!" exclaimed Barth, as he was stepping into the limousine. "But I shall not accept the latter part of your offer. As soon as I have reached my destination, I shall send the car back here. That is" - the commissioner paused - "unless -"

"Unless what?" queried Cranston, quietly.

"Unless you should care to go along," completed Barth. "Perhaps" - the commissioner's tone was slightly condescending - "perhaps you might be interested in observing the law at work."

"Very well," responded Cranston, with the slightest trace of a smile upon his thin lips. "Suppose I accompany you, commissioner."

With that he entered the car and pa.s.sed the speaking tube to Barth. The commissioner gave Stanley the address of Troxton Valdan's home. The limousine rolled northward, while Barth talked to Cranston. "I WAS summoned last night," explained the commissioner, "to view the scene of an extraordinary mystery. Of course you have read about it in the newspaper, Cranston. I refer to the strange death sleep that overpowered four victims."

"I glanced at the headlines," responded Cranston, "but I did not read the details. Are the victims recovering?"

"Their condition had not changed at three o'clock this afternoon. I received a report from the physician in charge - Doctor Seton Lagwood."

"I have heard of him. A specialist in such maladies as sleeping sickness."

"Yes. Somewhat radical in his methods of treatment, I understand, and therefore the very man to handle these cases."

"Why so?"

"Because the victims were overcome by what appears to be a new malady. A more conservative physician would not give these cases the thorough attention that Lagwood has exhibited. I believe that the coincidence was most fortunate."

"To what coincidence do you refer?"

"The episode," explained Barth, "took place in an apartment building not far from the Talleyrand Hospital.

Hence the victims were taken there for treatment. The Talleyrand chances to be the one Manhattan hospital that relies solely upon Doctor Lagwood in cases of this sort."

"Quite a coincidence," responded Cranston. "What of the case which now summons you, commissioner?"

"It concerns the death of a chemist named Troxton Valdan," stated Barth. "Nothing to do with last night's occurrence. We proved conclusively that crime was absent at the apartment of Seth Tanning. But there is evidence of crime at Troxton Valdan's.

"Detective Cardona - acting inspector for the present - is under instructions to notify me of any unusual cases that he encounters. He called me at the club to tell me of this one. It appears that Troxton Valdan was found dead in his laboratory; and the evidence balances between foul play and accidental death. The very type of case that requires my personal attention."

WHEN the limousine pulled up in front of Valdan's house, a policeman appeared and saluted the commissioner. The officer led the way up the brownstone steps and down the inner stairway into the large laboratory. Here Barth and Cranston were met by Joe Cardona, who led them into the smaller room. They viewed Valdan's body. Barth looked toward the police surgeon who had just completed an examination.

"Death was instantaneous, commissioner," reported the physician. "Caused by a fracture at the back of the skull. His head must have received a terrific blow."

"A fall from the ladder would have been sufficient?"

"Yes. The man looks like he was a healthy specimen; but he is certainly well along in his sixties. Vertigo would not be unexpected. The effort of climbing the ladder could have caused it."

"Then the evidence points to accidental death." Barth made this statement in a tone of a.s.surance. It brought a smile from Cardona, who was standing by.

The detective invariably encountered a problem when he dealt with the police commissioner. Barth had a tendency to be over-critical of Cardona's judgment; to form conclusions that were designed to belittle the detective's theories. In this case, Cardona had waited for Barth to form a half-baked decision; and the commissioner had fallen for the ruse.

"Quite simple," amplified Barth, turning to Cranston. "One must avoid the usual tendency that is a common fault of police investigators. The average detective attempts to connect crime with every death that he views.

"Here we have a dead man - well advanced in years - lying with fractured skull at the foot of a ladder. It is obvious that he opened that high drawer" - Barth pointed toward the ceiling - "and lost his balance.

The fall killed him. Of course, Cardona" - the commissioner smiled indulgently as he turned to the detective - "I must commend you for notifying me so promptly regarding this case. Even though my judgment merely supports the obvious conclusion, you showed wisdom in bringing me to this scene."

"Just a moment, commissioner," remarked the detective. "There is one point about this case that I didn't have a chance to explain. This room is not exactly as it was just after the death of Troxton Valdan."

"Ah!" Barth's countenance changed suddenly. "You mean that you have found some piece of evidence?

Or that something has been removed?"

"Neither," replied Cardona. "I have touched nothing."

"But you have made some change since your arrival?"

"None. The room is exactly as I found it. But it is not as it was when these men" - Cardona indicated Benzig and Crowder - "when these employees of Valdan's entered."

"What!" exclaimed Barth. "You mean that they deliberately muddied matters?"

"Not at all," declared Cardona. "On the contrary, commissioner, they performed a very simple and necessary action immediately after they opened the door."

"What was that?" demanded Barth, perplexed.

"They turned on the light," responded Cardona, with a smile.

WAINWRIGHT BARTH stood staring. His bald head glistened, while his eyes blinked through the pince-nez spectacles. Caught off guard, the commissioner was still puzzled. While Barth stood silent, Cardona spoke.

"Taking the obvious, commissioner," the detective stated, "we can agree that Valdan was on that ladder, looking through the file. But it is not logical that he was doing it without any light. You can't go through a filing cabinet in a pitch dark room."

"You should have told me this when I arrived," snapped Barth. "This places a different aspect on the entire case. Come; let me hear what the witnesses have to say."

"Here are their statements."

"Let them repeat them, in brief."