Now that they had decided on an explanation of their schoolfellow's mysterious conduct, the chums felt that every circumstance seemed to point in its favour. They wondered they had never thought of it before. The importance of keeping a strict watch was realized by both. There was a certain satisfaction in doing so. They felt as if they were rendering their country a service, almost indeed as if they were members of a secret diplomatic corps, and had been told off for special duty. Who knew what England might have to thank them for some day? Possibly at no very far-off date the whole country might be ringing with their names, and the newspapers publishing portraits of the two schoolgirls who had averted a national disaster. Just to be prepared for emergencies, they took snapshots of each other with Dulcie's Brownie camera, and added a series of photographs of the school, all of which they thought would be very suitable to give to the enthusiastic reporter who would demand an illustrated interview. They were rather disappointed with the results of the portraits, which in their estimation scarcely did them justice. "I look more like forty than fourteen!" said Deirdre, regarding ruefully the dark shadows on her cheeks and the lines under her eyes. "It doesn't show my hair properly, either. No one could tell it was curly." "And I look as fat as a prize pig, with no eyes to speak of, and an imbecile grin." "I wonder how real photographers manage to touch things up, and make them look so nice?" In spite of their best efforts it had proved impossible to do their developing and printing without their handiwork being seen by their companions. The photographs of the school were so good that the girls begged them shamelessly to send home. Gerda was particularly importunate, and even offered to buy copies when they were refused as a gift. "We don't sell our things," said Dulcie bluntly. "You may go on asking till Doomsday, and you won't get a single print, so there!" To the chums, Gerda's request was full of significance. "It shows pretty plainly we're on the right track," said Deirdre. "Of course she wants them to send to her foreign government. They'd pay her handsomely." "Don't she wish she may get them!" snorted Dulcie. The affair made an added coolness in their dormitory. Gerda appeared to think them unkind, while they stood more than ever on the alert. They watched her unceasingly. For some days, however, they could find nothing of an incriminating nature in her conduct. Possibly she was aware of their vigilance, and was on her guard against them. "I believe we're overdoing it," said Deirdre anxiously. "Best slack off a little, and seem as if we're taking no notice of her. Don't follow her about so continually. It's getting too marked altogether. We must be diplomatic."