Pamela went back to Moss Cottage with new courage. The secret, which had almost overwhelmed her when she had tried to bear it alone, assumed a different aspect now she shared it with her friends. Captain Harper had taken the full responsibility of the affair, and as one of His Majesty's officers she knew he could be trusted. She placed herself entirely in his hands, and followed his directions implicitly. To keep watch without arousing her uncle's suspicions was to be her present rôle. Under cover of going to tea with the Watsons, she met Captain Harper at Walden, and learnt from him the Morse code. Once she had mastered that, she was able to write down some of the wireless messages. To her they were absolutely unintelligible, for they were in cipher, but she made a faithful record of what she heard through the receiver, and sent it by David or Anthony to the young officer. For the moment Captain Harper acknowledged himself baffled. "We have the keys to a number of ciphers, but there's one here we don't understand. It's solely for this reason we're allowing this wireless apparatus at Moss Cottage to remain where it is. Pamela must use all her ingenuity to discover the key to the cipher. She's the only person who has the opportunity of doing so. If we were to arrest Mr. Hockheimer at once we might or might not find treasonable papers upon him. It is doubtful if we should learn his secret." To David and Anthony the affair was of the supremest interest. They envied Pamela her unique chance of serving her country. They were glad enough to be employed as carriers, and would take the notes from her when they met her in the morning, and, according to arrangement, convey them to Captain Harper. Sometimes they took them direct to the Camp, after they returned from school, and sometimes they handed them to an orderly who would be strolling about near the station. As for Pamela, she lived from day to day in a ferment of expectation, waiting and watching for her opportunity. And one evening she found it. Mr. Hockheimer had come, as was his custom, to Moss Cottage, and had set his niece to listen for messages while he took his ease in the house. For an hour or more Pamela had sat with the receiver to her ears, but had heard nothing. At last came the familiar humming. She jotted down the letters, put the paper safely in her pocket, and ran up the garden to warn her uncle. That night he had been drinking more heavily than usual. He lurched in his walk as he approached the stable, and it was with difficulty that he climbed the ladder. Pamela followed him nervously. His hands shook as he fitted on the receiver, but he nevertheless took down the message. Then he paused, and seemed to be calculating something out on the paper. She crept a little nearer. He was too muddled to realize her approach. She peeped over his shoulder unnoticed. In his half-drunken condition he was working out the cipher and writing it down. She copied it word by word.