It was almost in place, and the bent timber was getting loose, when the top slipped and shook the beam.

There was an ominous crack and a few small stones broke away and fell on Scott's head.
"I've got her butted solid now," he shouted after a short breathless struggle with the timber.

"Be quick! The roof's coming down!" Thirlwell saw the danger.

So long as the prop slanted, it would not support the beam, and if the beam gave way, the roof would fall and crush them before they could get from underneath.

He thought he had a few moments to hammer the prop straight, and swung the ax savagely while the sweat ran down his face.