“I want you to measure the glass of the lamp. Do not go up any higher than is necessary, but if you have to stretch be careful not to mark on the measurement with your nail, although the impulse is a natural one. That has been done already.”

Parkinson looked apprehensively around and about. Fortunately the part was a dark and unfrequented spot and everyone else was moving towards the exit at the other end of the platform. Fortunately, also, the signal was not a high one.

“As near as I can judge on the rounded surface, the glass is four and seven-eighths across,” reported Parkinson.

“Thank you,” replied Carrados, returning the measure to his pocket, “four and seven-eighths is quite near enough. Now we will take the next train back.”

Sunday evening came, and with it Mr Carlyle to The Turrets at the appointed hour. He brought to the situation a mind poised for any eventuality and a trenchant eye. As the time went on and the impenetrable Carrados made no allusion to the case, Carlyle’s manner inclined to a waggish commiseration of his host’s position. Actually, he said little, but the crisp precision of his voice when the path lay open to a remark of any significance left little to be said.

It was not until they had finished dinner and returned to the library that Carrados gave the slightest hint of anything unusual being in the air. His first indication of coming events was to remove the key from the outside to the inside of the door.

“What are you doing, Max?” demanded Mr Carlyle, his curiosity overcoming the indirect attitude.

“You have been very entertaining, Louis,” replied his friend, “but Parkinson should be back very soon now and it is as well to be prepared. Do you happen to carry a revolver?”

“Not when I come to dine with you, Max,” replied Carlyle, with all the aplomb he could muster. “Is it usual?”

Carrados smiled affectionately at his guest’s agile recovery and touched the secret spring of a drawer in an antique bureau by his side. The little hidden receptacle shot smoothly out, disclosing a pair of dull-blued pistols.