Danny the Detective by Vera C. Barclay — Read

And meanwhile, what of Danny! Was he sharing in the pride and joy of the Pack, in its important work? No; Danny was not feeling very cheerful, for he was conscious that for the first time since he had been a Cub he was failing to do his duty. Why? Because he was _giving in to himself_, to his own pride and ambition, and thinking of his own glory before the safety of his country.

Here he was, knowing a large number of important particulars about a dangerous gang of spies. He knew their hiding-places; their footprints; the faces and appearance of several of them. He knew mysterious things about them that he did not understand. His country was in great peril; the Scouts were called out to try and catch these very Germans -- while he kept his secret to himself. A voice inside him said: