Then she remembered Slinky's threat to tell Mrs. Warrender and Mrs. Morton about last night's adventure. Perhaps he had already done this and that was why her aunt had seemed so quiet and suspicious just now? And yet it did not seem likely that he would risk doing such a stupid thing merely out of spite, particularly as he must have been certain that Jon would betray him if forced to do so.

She paused outside her aunt's sitting-room and listened hopefully. Jon was down, for she could hear his voice raised rather querulously, and as Penny recognized this sign she was certain that unless he was supported he was in the mood to give everything away!

By the time Penny sat down at the table Jon had started to say:

"Mother, I think perhaps we ought to tell you..." And then two things happened. First, Penny kicked out under the table in the hope of reaching her cousin, and then there was a knock at the door and Mr. Grandon came in. He looked more sallow than usual this morning and his black eyes flickered quickly from Jon to Penny as he said quietly to Mrs. Warrender:

"Excuse me. The telephone. They insist upon speaking to you and say it is urgent... I am so sorry. I did not know that you were still at breakfast..." He held the door open for her then, when she had gone out, he turned to Jon and Penny and put his finger to his lips.

As soon as he had closed the door Penny opened her mouth to speak, but Jon whispered:

"Quiet for a minute. He may be listening outside."

Penny tip-toed to the door and put her mouth to the keyhole, took a deep breath and blew through it!

"If he's there now that'll give him earache!" she announced with great satisfaction, then turned like a fury on her cousin.

"Now then," she went on, "you were going to give in, weren't you? You were just going to tell her, and I bet Slinky was listening outside then and invented the telephone so that you would be interrupted. It's too bad of you, Jon! You know you promised you wouldn't tell her."

"Look here, Penny," Jon said, "this is all very well, but I think this business has got too serious for us and that Mother ought to know that this beastly man Slinky is an accomplice of Miss Ballinger's. She ought to know, too, that this proves there is a treasure and that they tried to bribe me with a motor-bike..."

"Jon! You know you promised that we would do this without the grown-ups, and now we've got the Mortons to help there's no need to be afraid of anybody. We'll find the treasure without grown-ups. I know we will."

But Jon just shook his head obstinately.