Dorothy Dale to the Rescue by Margaret Penrose

Roger looked chagrined and more than a little frightened. The fright was caused by his sister's vehemence, the chagrin because he had unwittingly "told on" Joe. In the code of Roger no crime was as bad as that of "telling tales" on one's mates. He had spoken before he thought. It is so hard for a small boy not to speak before he thinks!

But Dorothy was on her feet now, her cheeks blazing, and he knew he would have to tell her the truth, not keeping back any of the story. Roger gave a resigned sigh and braced himself to answer questions. But Dorothy asked only one of him. That was a reiterated and breathless: