More or less the drought had lasted since April. Tales came up from the provinces of stagnant rivers and quick, fell spurts of zymotic diseases. For a long time past the London water companies had restricted their supplies. Still, there was no suggestion of alarm, nothing as yet looked like a water famine. The heat was almost unbearable but, people said, the wave must break soon, and the metropolis would breathe again. Professor Owen Darbyshire shook his head as he looked at the brassy, star-powdered sky. He crawled homewards towards Harley Street with his hat in his hand, and his grey frock coat showing a wide expanse of white shirt below. There was a buzz of electric fans in the hall of No. 411, a murmur of them overhead. And yet the atmosphere was hot and heavy. There was one solitary light in the dining-room--a room all sombre oak and dull red walls as befitted a man of science--and a visiting card glistened on the table. Darbyshire read the card with a gesture of annoyance: James P. Chase _Morning Telephone_ "I'll have to see him," the Professor groaned, "I'll have to see the man if only to put him off. Is it possible these confounded pressmen have got hold of the story already?" With just a suggestion of anxiety on his strong clean-shaven face, the professor parted the velvet curtains leading to a kind of study-laboratory, the sort of place you would expect to find in the house of a man whose speciality is the fighting of disease in bulk. Darbyshire was the one man who could grapple with an epidemic, the one man always sent for. The constant pestering of newspaper men was no new thing. Doubtless Chase aforesaid was merely plunging around after sensations--journalistic curry for the hot weather. Still, the pushing little American might have stumbled on the truth. Darbyshire took down his telephone and churned the handle. "Are you there? Yes, give me 30795, Kensington.... That you, Longdale? Yes, it's Darbyshire. Step round here at once, will you? Yes, I know it's hot, and I wouldn't ask you to come if it wasn't a matter of the last importance." A small thin voice promised as desired and Darbyshire hung up his receiver. He then lighted a cigarette, and proceeded to con over some notes that he had taken from his pocket. These he elaborated in pencil in a small but marvellously clear handwriting. As he lay back in his chair he did not look much like the general whose army is absolutely surrounded, but he was. And that square, lean head held a secret that would have set London almost mad at a whisper. Darbyshire laid the sheets down and fell into a reverie. He was roused presently by the hall bell and Dr Longdale entered. The professor brightened. "That's right," he said. "Good to see somebody, Longdale. I've had an awful day. Verity, if Mr. Chase comes again ask him in here." "Mr. Chase said he would return in an hour, sir," the large butler replied. "And I'm to show him in here? Yes, Sir."