Tarling dropped the telephone receiver on its hook and had sunk into a chair with a groan. His face was white--whiter than the prisoner's who sat opposite him, and he seemed to have gone old all of a sudden.

"What is it?" asked Whiteside quietly. "Who was the man?"

"Stay," said Tarling. "Stay. He has Odette! It's awful, awful!"

Whiteside, thoughtful, preoccupied; Milburgh, his face twitching with fear, watched the scene curiously.

"I'm beaten," said Tarling--and at that moment the telephone bell rang again.

He lifted the receiver and bent over the table, and Whiteside saw his eyes open in wide amazement. It was Odette's voice that greeted him.

"It is I, Odette!"

"Odette! Are you safe? Thank God for that!" he almost shouted. "Thank God for that! Where are you?"

"I am at a tobacconist's shop in----" there was a pause while she was evidently asking somebody the name of the street, and presently she came back with the information.

"But, this is wonderful!" said Tarling. "I'll be with you immediately. Whiteside, get a cab, will you? How did you get away?"

"It's rather a long story," she said. "Your Chinese friend saved me. That dreadful man stopped the cab near a tobacconist's shop to telephone. Ling Chu appeared by magic. I think he must have been lying on top of the cab, because I heard him come down by the side. He helped me out and stood me in a dark doorway, taking my place. Please don't ask me any more. I am so tired."

Half an hour later Tarling was with the girl and heard the story of the outrage. Odette Rider had recovered something of her calm, and before the detective had returned her to the nursing home she had told him the story of her adventure.

"I must have fainted," she said. "When I woke up I was lying at the bottom of the cab, which was moving at a tremendous rate. I thought of getting back to the seat, but it occurred to me that if I pretended to be faint I might have a chance of escape. When I heard the cab stop I tried to rise, but I hadn't sufficient strength. But help was near. I heard the scraping of shoes on the leather top of the car, and presently the door opened and I saw a figure which I knew was not the cabman's. He lifted me out, and fortunately the cab had stopped opposite a private house with a big porch, and to this he led me.

"'Wait,' he said. 'There is a place where you may telephone a little way along. Wait till we have gone."

"Then he went back to the cab, closed the door noiselessly, and immediately afterwards I saw Stay running along the path. In a few seconds the cab had disappeared and I dragged myself to the shop--and that's all."

No news had been received of Ling Chu when Tarling returned to his flat. Whiteside was waiting; and told him that he had put Milburgh into the cells and that he would be charged the following day.

"I can't understand what has happened to Ling Chu. He should be back by now," said Tarling.

It was half-past one in the morning, and a telephone inquiry to Scotland Yard had produced no information.

"It is possible, of course," Tarling went on, "that Stay took the cab on to Hertford. The man has developed into a dangerous lunatic."

"All criminals are more or less mad," said the philosophical Whiteside. "I wonder what turned this fellow's brain."

"Love!" said Tarling.

The other looked at him in surprise.

"Love?" he repeated incredulously, and Tarling: nodded.

"Undoubtedly Sam Stay adored Lyne. It was the shock of his death which drove him mad."

Whiteside drummed his fingers on the table, thoughtfully.

"What do you think of Milburgh's story?" he asked, and Tarling shrugged his shoulders.

"It is most difficult to form a judgment," he said. "The man spoke as though he were telling the truth, and something within me convinces me that he was not lying. And yet the whole thing is incredible."

"Of course, Milburgh has had time to make up a pretty good story," warned Whiteside. "He is a fairly shrewd man, this Milburgh, and it was hardly likely that he would tell us a yarn which was beyond the range of belief."

"That is true," agreed the other, "nevertheless, I am satisfied he told almost the whole of the truth."

"Then, who killed Thornton Lyne?"

Tarling rose with a gesture of despair.

"You are apparently as far from the solution of that mystery as I am, and yet I have formed a theory which may sound fantastic----"

There was a light step upon the stair and Tarling crossed the room and opened the door.

Ling Chu came in, his calm, inscrutable self, and but for the fact that his forehead and his right hand were heavily bandaged, carryi............