By this time the sound of firing had died away save for an occasional distant boom, and as it would be useless to try and locate the scene of action now, Lawless did the best thing possible in following the ship which had so nearly run him down. If she were a British cruiser no harm would be done; while, were she German--well, there would be some exciting moments in store for both. So far, however, her nationality could not be ascertained, and so Lawless, guided by the sound of her engines, kept abreast of her as near as he could judge. While the fog lasted he could not hope to identify her by sight, but a chance occurrence, such as a bugle call, a loud order given on deck, or a call on the pipe, might afford a clue. Meanwhile it was necessary to prevent those on board from suspecting the presence of a destroyer so close at hand, for, should the _Knat_ be sighted, the chances were a hundred to one that, friend or foe, the strange vessel would open fire on her without waiting to make inquiries. For nearly an hour the two vessels continued to pound along in a south-easterly direction, each hidden from the other by the enveloping fog. "Something's got to be done," said Lawless at last. "In my opinion she's a German, for she's certainly laying a course towards Heligoland, and if we're not mighty careful we'll find ourselves in a trap. Point is, how the devil are we to make the skipper give himself away?" "Send a wireless in English. If he's----" "No good," broke in the Lieutenant. "If he's a German he'd savvy the dodge and play up to us." The fog was now beginning to show signs of clearing overhead, though it still lay thick upon the sea. There was every prospect of its soon disappearing altogether, and then, perhaps, the mystery of the unknown vessel would be solved and her fate--or that of the _Knat_--decided. "Look!" shouted Trent abruptly, but before Lawless could follow the upward direction of his gaze something fell in the water just astern and then came the sound of a loud explosion. Others followed in quick succession, some of the bombs falling so close to the destroyer that the men standing by the torpedo tubes were drenched by the water they threw up. There was no need to inquire as to the cause of these unpleasant phenomena, they were due to a Zeppelin hovering above--probably the same one which had been encountered earlier in the day. "That settles it," said Lawless. "We're in company with a German cruiser and her guardian angel."