"Oho, Miss Netta Goodwin! What's the matter with you?" thought Ida. "You have an uncommonly guilty look about you, almost as if you were committing a crime. What's up, I wonder? I think I'm just going to track you and see." Since the stormy episode on the day when the Second Form girls were rehearsing for their morris dance, Ida Bridge had detested Netta. She felt she owed her a grudge, which she was most anxious to pay if a reasonable opportunity could only be found. She followed now post haste, and adopting the tactics of a scout, waited till Netta was safely inside the Fifth Form room, then peeped cautiously round the door. What she saw did not particularly enlighten her. Netta was busily tearing sheets of notepaper in half, was scribbling something on them, blotting them and putting them into envelopes. No one else was in the room, and there was nothing to suggest an explanation of this rather mysterious employment. "I'm sure she's up to something, though," murmured Ida to herself, still keeping a watchful eye on the enemy's movements. Netta wrote away, and kept folding her pieces of paper with record speed; there was a complacent look on her face, and she chuckled occasionally, as if with deep satisfaction. At the sound of the dinner bell she started, and hurriedly swept her correspondence into her desk. Ida, with admirable presence of mind, bolted into the empty Sixth Form room opposite, and having seen Netta depart down the corridor, took the liberty of going to make an inspection of what she had been doing. "Um--indeed! What have we here?" said Ida, opening the desk. "Envelopes marked with a V, and sheets of paper with names on. Let's take a look at them. 'Hilda Browne--Netta Goodwin.' 'Netta Goodwin--Gwen Gascoyne.' 'Betty Brierley--Netta Goodwin.' 'Charlotte Perry--Netta Goodwin.' All in such different styles of writing, too! I believe I begin to see daylight. Now, shall I go and call Miss Douglas at once to look at this? No--it's incriminating, but not sufficient evidence to convict. I must let things develop a little further first. I think I'd better have a witness, too. Miss Netta Goodwin, I believe you're going to be rather too clever for once, and that you'll find yourself outwitted by one of the despised Juniors." Ida Bridge was late for dinner that day, but she took Miss Roscoe's reproof with a sangfroid at which her Form marvelled. "I don't care if I have to write fifty lines as a punishment," she murmured to her neighbour and chum, Peggy Weston. "What I've just discovered is worth a thousand lines. I can't explain why now, but the moment dinner is over you and I must stalk Netta Goodwin, and, without letting her know it, never take our eyes off her till afternoon school begins."