"Be quiet, David! Wait a minute, else you'll have them all out here wondering what the noise is about. We've got to go straight back to Onnybrook. There's not a minute to spare. We've found something important and I must get you kids out of the way..."

"But they're here, Uncle," Tom interrupted. "We're sure of it. I heard the dog bark."

"Nonsense," said his uncle. "You're tired and imagining things. Come on. We must be off at once."

David stood firm. He suddenly felt better and was as confident as Tom about Macbeth.

"Mr. Ingles," he pleaded, "we just can't go and leave them... I'm sure they're here. I know that was Mac's bark and I know Mary would never leave him. They're in this house somewhere and we must try now and find them. Please!"

Mr. Ingles hesitated. He had his own ideas now as to what was going on in this house, and he knew he had no time to waste. He had not heard the dog, but both the boys seemed confident, and if there was a doubt he could hardly leave without making sure.

"Quickly, now!" he whispered suddenly. "Think, young Tom. Where do you think the dog would be?"

Tom scratched his head. "Indoors," he said at last. "Not here at the front. Seemed a long way away. Shall I whistle again? Maybe he'll bark back."

"No, not yet. We'll search the back of the house again. Come along," and he led the way quickly round the side of the house. At the back was a paved yard where David blundered into a water-butt. Here it was darker than ever, and Tom said, "Haven't you got a torch, Uncle? Let's look and see if any windows are open upstairs."

"I didn't look for that before, Tom. Good idea. Here goes," and he swung the narrow beam up the wall. They watched the little spot of light travel over the ivy until it picked out a stone ledge. Mr. Ingles raised the torch a few inches and the light was reflected back from glass. A window - and one half of it just open. He switched out the torch and in the darkness Tom whistled softly again the peewit's call. His uncle gripped his arm in surprise and annoyance, but Tom was justified, for from the window above there came Mac's throaty growl.

"Oh, gosh!" David whispered. "He'll bark. How are we going to stop him barking? Listen and see if the twins are there."

But there was no other sound, and then David had a big idea.

"Lift me on your shoulders, Mr. Ingles, and I can reach the window. I'll keep Mac quiet if I can speak to him and if you'll give me your torch I can see if they're in that room. If we're not quick maybe he'll bark again "

"All right, boy, but look sharp. We've got to get back soon. Off with your shoes... Now help him up, Tom."