He wanted three minutes, he wanted them very badly; perhaps two minutes would be enough. All the time the lawyer was speaking he was actively employed. He had kicked off his shoes when the lights went out, and now he stole round the room, his sensitive hands flying over the stony walls.

“As to my intentions,” the lawyer was saying, “it must be fairly obvious to you that I am not going to hand you over to the police. Rather, my young friend, in the vulgar parlance of the criminal classes, I am going to ‘do you in,’ meaning thereby, if you will forgive the legal terminology, that I shall assist you to another and, I hope, though I am not sanguine, a better world.”

He heard Jimmy’s insolent laugh in the blackness.

“You are a man after my own heart, Jimmy,” he went on regretfully. “I could have wished that I might have been spared this painful duty; but it is a duty, one that I owe to society and myself.”

“You are an amusing person,” said Jimmy’s voice.

“I am glad you think so. Jimmy, my young friend, I am afraid our conversation must end here. Do you know anything of chemistry?”

“A little.”

“Then you will appreciate my burglar catcher,” said Spedding, with uncanny satisfaction. “You, perhaps, noticed the japanned box with the perforated lid? You did? Good! There are two compartments, and two chemicals in certain quantities kept apart. My hand is on the key now that will combine them. When cyanide of potassium is combined with sulphuric acid, do you know what gas is formed?”

Jimmy did not reply. He had found what he had been searching for. His talk with the Spanish builder had been to some purpose. It was a little stony projection from the wall. He pressed it downward, and was sensible of a sensation of coldness. He reached out his hand, and found where solid wall had been a blank space.

“Do you hear, Jimmy?” asked the lawyer’s voice.