Mike Murphy had slipped so silently from among them that no one was aware of his absence when the b.u.mping and crash at the rear were followed by exclamations and words that were not intelligible. Mrs. Friestone uttered a faint cry and sank back on her chair. Nora screamed and threw her arms about her mother's neck.

"They will kill us! What shall we do?" she wailed.

For the moment Alvin and Chester, startled almost as much as their friends, were mystified. When Chester said:

"That sounds like Mike's voice. h.e.l.lo, Mike, are you here with us?"

The failure to receive a reply proved that Chester was right. Their comrade had stolen off and was already in a "shindy" at the rear of the store.

"He may need our help!" called Alvin, starting for the stairs, with his chum at his heels. But Nora, who had heard the unguarded words, called in wild distress:

"Don't leave us! Don't leave us!"

They stopped irresolute. They could not abandon the two, and yet Mike's life might be in peril.

"Go back to them," whispered Chester. "There's no call for both of us to stay."

"Better not go down yourself; you know you have no weapon. Let's take a look."

First of all it was necessary to quiet the daughter and mother, for one was as much terrified as the other. Alvin hastened into the room.

"We will not leave you," he said, "but we wish to see what we can from the kitchen window."

"Oh, you may fall out," moaned Nora, scarcely responsible for what she said. Even in the crisis of a tragedy a vein of comedy will sometimes intrude itself.

"Have no fear of that," replied Alvin. "I will hold Chester from tumbling out and he will do the same for me. Pray, compose yourselves."

During this brief absence Chester had threaded his way past the furniture in the darkness to the window, out of which he was gazing on a most interesting moving picture which had vanished when Alvin appeared at his elbow.

"It made my blood tingle," said Chester. "I was just in time to see a man, who must have leaped out, running for life with Mike in pursuit. He had that old gun in one hand--as if it could prove of any earthly use to him."

"Where are they now?"

"The fellow, after leaping the fence, turned to the right and disappeared among the shadows."

"With Mike still chasing him?"

"As hard as he could run, but you know he hasn't much speed."

"I wonder," whispered Alvin, "whether there are any more of them downstairs."

They stepped noiselessly to the head of the steps and listened.

Everything was so quiet that they heard the ticking of the clock on the wall of the store.

"I don't believe anyone is there. Let's take a closer look."

Alvin struck a match from his safe and led the way, thus saving the two from the mishap that had overtaken their friend. They were a trifle nervous when they stepped upon the lower floor, Alvin maintaining the illumination by burning more matches. He climbed upon the counter, and lighted the large oil lamp suspended there for such purpose. Adjusting the wick to the highest point it would stand without smoking, the two looked around.

What they saw completed the story that had already taken shape in their own minds. The unbroken dark lantern lay on the floor where it had fallen, the light having been extinguished. The raised window showed by what avenue the burglar and Mike had left the building, but what amazed the youths more than anything else was the wide open door of the safe.

Not a burglar's tool or device was in sight, and the appearance of the lock and door without a scratch showing proved that no part of the structure had been tampered with. It was just as if Mrs. Friestone had manipulated it--as she had done times without number.

"Whoever opened it must have known the combination. And how did he learn it?"

Chester shook his head.

"Perhaps Mrs. Friestone can guess. I'll ask her."

Going to the foot of the stairs, the young man called to the woman just loudly enough for her to hear. He said the visitors had left, but the door of the safe was open and it was advisable for her to come down and take a look at things.

She timidly came down the steps, with Nora tremblingly clinging to her skirts, ready to scream and dash back to the front of the house on the first appearance of danger. But nothing occurred to cause new alarm, and mother and daughter stared wonderingly at the safe with its wide open door.

"Who did that?" asked the woman, in a faint voice.

"One of the burglars," replied Chester.

"How did he learn the combination?"

"That's the mystery; Alvin and I cannot guess. Was it known to anyone besides yourself?"

"No; I changed it two days ago and did not even tell Nora. Not another soul knew it--and look!"

She pointed to a bunch of keys, one of which was inserted in the lock of the middle small drawer, with a half dozen others dangling from the metal ring. It will be understood that while the door of the safe was opened by means of a usual combination of numbers, the interior was guarded by only a tiny lock and key. This was more convenient, for, when the ma.s.sive door was drawn back, the little wooden drawers, even with a combination, would not avail long against a burglar.

"They have taken the money!" gasped the widow.

"Let us see."

As Alvin spoke, he turned the key. The lock clicked and he drew out the drawer. There lay the big sealed envelope with the two thousand five hundred dollars intact within, while the stamps and cash receipts of the day were neatly piled on the shelf beneath.

The astonishing truth was that the criminal had been interrupted at the critical moment when he had succeeded in fitting a key to the lock. Had Mike Murphy been the fraction of a minute later in bursting upon the scene, he would have been too late. The robber would have carried off nearly three thousand dollars.

"That's what I call the greatest luck that ever happened," said Chester.

The discovery was as cheering as amazing. The large amount of money had been saved by a hair's breadth. The woman clasped her hands in thankfulness. Chester slowly shoved the steel door shut.

"Now try the combination," he said to Mrs. Friestone. "Chester and I will turn our backs while you do so."

"And why will you do that?"

"So that we shall not learn the secret. If anything like this happens again, you cannot say we did it."

She saw the smile on his face and knew he spoke in jest.

"It may be the lock was broken in some way," suggested Chester.

But it worked perfectly. The k.n.o.b was turned forward till the finger pointed to a number, then back and then forward again to another numeral.

It moved as smoothly as if the delicate mechanism was oiled.

"Now open it," she said to the lads, her spirits rallying over her good fortune. They shook their heads and Chester said: