It was then that he noticed a white square of paper on the carpet just inside the door. There was no name or address on this, but "Very Private" was scrawled across one corner in indelible pencil. Jon thought he recognized the writing and, realizing that there would not be much more rest for him now, he put on his dressing-gown and sat on the edge of the bed.

"JON," he read. "I have been thinking again and this is all VERY SERIOUS. Slinky must be watched all the time, and very specially today before he goes out to meet Miss B. at the old mill. Have you thought which mill? Remember he told her that he would have the papers. Have you still got the clue safely? I know you will be snoring right up to breakfast time and you were so shirty when I woke you yesterday that I'm writing this instead, but we have got to DOG Slinky today without fail. I am going downstairs now to find him and I will keep him talking till you come or until breakfast time."

"Penny."

"Oh, gosh!" Jon muttered to himself as he tore the note into small pieces and threw them into the wastepaper basket thoughtfully provided by his mother. "Oh, gosh! I had a feeling she'd be up to something. She's probably sitting outside his bedroom door waiting for him to come out."

Then he washed and dressed as quickly as he could and went downstairs. Penny was not in the lounge and neither was Fred, so he went out into the yard. His mother's front door was locked; he lifted the flap of the letter-box and bent down in the hope of seeing through into the hall. Just at that moment the door shifted slightly under his hand and began to open inwards, and he heard Penny say softly and sweetly:

"Good morning, Mr. Grandon. I just happened to be passing in the hall and heard you try the door. It's a much nicer morning, isn't it? I'm so glad..."

"Don't be an idiot, Penny," Jon interrupted. "Open the door properly and let me in."

"Jon!" she gasped. "I thought it was Slinky. I thought it must be Slinky... I hoped it was anyway," she added in a burst of candour.

Jon squeezed past her and shut the door behind him. "What are you supposed to be doing anyway? Suppose I had been Grandon? What would you have done?"

"I should have engaged you in conversation," Penny said coldly. "And what are you doing here, might I ask?"

"You might well ask! I found your silly note and came right away to find you, although why I wasted my time I don't know."

"You've said that before," Penny said brightly. "But what note do you mean?"

Jon sat on the stairs and pulled her down beside him.