"What I'm so wild about," Jon added at the end of the story, "is that my leg hurt so much that I couldn't get down to see the girl who was with him. She sounded young but, of course, you can't tell from just a voice."

Penny said, "I knew you'd have all the adventures, and that's why you sent me to the mill with the goat. I know it is. Anyway, I'm sure we're right about Miss Ballinger. She's in it. She knows all about it. I always thought so, and now I'm sure. She was the one they had to take the papers to."

"But why should she send the girl when she was sitting only a few hundred yards away herself?" Jon asked. "Why go to all that trouble?... Still, I must admit that she's a very odd person. She was most curious about us again when I spoke to her on my way back. By the way, she's going to ask us to tea. Can't think why. Shall we go?"

"Of course we will. I wouldn't miss it for anything. But the greatest mystery of all is how Slinky got into our room and took the clue while we were at church. He must have another key, and I suppose we shall have to ask Auntie to let us change the lock. Jon, I bet that footprint in the dust was Slinky's! He's been there lots of times."

"Maybe he has, but I don't think he's ever been able to open the box. I suppose I must have dropped the clue when we rushed out to church. I think I'll slip up now and get the map. It's safer with us than in that room, and we'll have another good look at it when we're out... You go and see if the sandwiches are ready, and don't forget a bottle of something because picnics always make me thirsty," and he wandered off indoors, leaving Penny still leaning against the wall.

She was wondering whether it was worth going into the kitchen yet when she noticed a boy wobbling down Trader's Street towards her on a bicycle. He looked over to Penny and jerked his head towards the hotel.

"Where's door?" he asked curtly.

"In the wall," Penny answered sweetly. "It always is."

The boy glowered at her and muttered something which she could not hear, and got off the bicycle Then he took a letter from his pocket and after some intense mental effort turned in under the archway. He did not look like an errand boy, and as Penny was by nature very curious, she followed him into the yard, where he was now standing on the cobbles looking sulkily first at one door and then at the other.

"I wonder if I can help you?" Penny asked in her very best manner and held out her hand for the letter. The boy looked at her with deep suspicion and then said: