"Well, we must be dad's detectives and keep a sharp look-out, Alf," said little Bert with pride, and his brother assented.
The next day or two passed quietly enough, but on the third night something happened.
The two boys were awakened about eleven o'clock by the sound of men's voices, loud and angry. Their bedroom was over the office, and it was from the office that the sounds came.
Always now on the alert, Alf and Bert quickly got into their dressing-gowns and soft slippers and stole down the wide staircase of the big, two-storeyed house. The office door stood open, the lights were burning, and peering in unperceived from the dark hall, the boys saw Anton Griboff, his friend Stepan the fitter, and a third man, a fierce, rough-looking fellow, with a broken nose and a large red scar that cut across both cheeks on a line with the mouth, giving the appearance of a hideous grin from ear to ear.
The three ruffians were standing before the manager, and the boys heard Anton say: "We have come for the key of that safe, and we mean to have it. Give it up."
"The money in the safe is not mine, and I hold the key in trust," replied Mr. Oliver firmly. "You shall not have it."
Anton made a sign, and the other men suddenly sprang upon Mr. Oliver and held him, while Griboff searched the pockets for the key. In a moment, with a cry of triumph, he held it up.
But the next instant, he suddenly fell violently forward, struck his head sharply against the big open desk, and lay still, the cause of this being that Alf and Bert, creeping in on their hands and knees behind Griboff, just as he found the key, each seized a leg and pulled back with all their might. As the man's burly form came crashing down, the key of the safe dropped from his hand, and Alf pounced upon it and passed it on to Bert.
"Run and hide it," he whispered, "while I try to help dad."
The struggles of the manager were vain. The two rascals, taking no heed of their fallen comrade, proceeded to tie Mr. Oliver's arms to his side, and his ankles together. Alf, behind them in the dark doorway, and unseen by the ruffians, dared not speak, but his father saw him, and gave him a look which the boy rightly understood to mean that he was to go and get help.