"How many electricians came in?" he asked, over the short phone. "Four? Three workmen in jumpers and overalls and the manager? Frock coat and silk hat? All right. Be certain that only four go out. That's all."
He turned to Dr. Ransome and Mr. Fielding.
"We have to be careful here—particularly," and there was broad sarcasm in his tone, "since we have scientists locked up."
The warden picked up the special delivery letter carelessly, and then began to open it.
"When I read this I want to tell you gentlemen something about how—Great Caesar!" he ended, suddenly, as he glanced at the letter. He sat with mouth open, motionless, from astonishment.
"What is it?" asked Mr. Fielding.
"A special delivery letter from Cell 13," gasped the warden. "An invitation to supper."
"What?" and the two ot
