“Yes,” said Donald, “and—I believe I know who the other spy is.”

“Who?” said Eric, turning on his companion.

“Jenkins,” said Donald.

“By Jove, I believe you are right,” said Eric. “Jenkins—Uncle William’s servant. I always hated that sneaking Jenkins, with his prying ways and long nose. All the servants hate him, too. And now I come to think of it, he was always having long, private talks with Uncle William. Let’s get after him.”

The two boys crept downstairs, and through a door in the hall into the servants’ quarters. Whom should they run into but Jenkins, himself—Jenkins, in a bowler hat, carrying a little black bag.

“Where are you going?” asked Eric.

“To London, Master Eric,” said Jenkins, with his most innocent air.

“Why?”

“On business for Mr. Mendel. I mustn’t stop, sir, or I shall miss my train.” He pushed past the boys towards the door.

Eric was in despair—what should he do? “Mr. Mendel’s business,” in London was sure to be spy work. And if Jenkins went to London, to-day, he might hear of his master’s capture and never come back. Suddenly an idea came to him. He stepped forwards between Jenkins and the door.