An hour later, Dick and Yvette, seated in the helicopter, were in full flight for England. Yvette was at the controls; Dick, in view of the work that might be before them, crouched over the tiny machine gun which peered from the bow of the machine.
Professor Fortescue was in a terrible state of distress. He had been working in his laboratory, when a slight noise had caused him to turn round. A man, apparently a foreigner as the Professor judged from the hasty glance he got at him, was standing close behind him. Before the Professor could speak or move he received a violent blow on the head, and remembered nothing more till he recovered consciousness some time later under the care of the police.
His chief concern was for the radium, and his distress at its loss was pitiful. It was a disaster from which he seemed unable to recover. But he appeared to derive a strange satisfaction from the danger in which the thieves would find themselves.
“I don’t know how they will get it away,” he declared to the police inspector. “It was dangerous to stay very near the safe for long owing to the terrible power of the radium rays. If the thieves try to carry the tubes in their pocket they will not get very far. Surely they cannot realise the terrible risk they are running. However, that need not distress us; all we want is to get the radium back.”
In the meantime a strong party of police had arrived from Durham at the Professor’s house, and, under the guidance of the old shepherd, started across the moors for the spot at which the strange aeroplane had been seen. It was slow going over rough and difficult ground which tested the endurance even of the younger men. The only unconcerned person was the old shepherd who trudged stolidly on at a pace with which they found it difficult to keep up.
They had gone eight or nine miles before the old man spoke.
“Not far now,” he said.
A mile farther on he halted.
“It’s just over yon hill,” he said, pointing to a small eminence a few hundred yards away. “You will see it as soon as you get at the top.”