The Professor frowned. “I do not usually mistake a spot which I wish to remember,” he replied. “However, it was nearly dark when I left it, and I may have made an error of a few yards. As you can see, this track leads straight to those ruined walls, which are the remains of Morlandson’s laboratory. It was in that direction that the man made off. If you follow the path, you are sure to find the tracks further along.”

They resumed their way, Hanslet examining every foot of the path as they proceeded. It was not until they reached the ruined posts which had marked the limits of the front garden that Hanslet turned and looked anxiously at the Professor.

“You are quite sure that this was the path he followed?” he asked. “I can’t see any tracks along it at all, either of your feet or of the bicycle.”

“Perfectly certain,” replied the Professor stiffly. “I am not likely to mistake it, especially as it would appear to be the only path in the vicinity.”