"Can't understand it," replied Barcroft Senior. "Why Norton should bolt out of my house and desert his own all night is a complete puzzle. I can only put forward the theory that the Zep. raid made him lose his mental balance--and he's a fellow with a steady head, I fancy. If he doesn't put in an appearance before lunch time I feel it is my duty to report the circumstances to that pillar of intelligence the Tarleigh police sergeant." "And possibly get yourself arrested on suspicion," chuckled Entwistle. "Norton was last seen in this house, remember." "It would be an experience that would afford practical knowledge as far as my work is concerned," decided Peter. "Nothing like real life to work into a plot, you know." Breakfast over, Entwistle and the flight-sub went out into the garden for the time-honoured matutinal pipe until it was time for Peter's guest to take his departure. "Come along, Billy," shouted his father. "Bear a hand at getting Butterfly harnessed." The flight-sub was in mufti. His uniform had been damaged beyond repair during his toil amidst the ruins of that devastated street in Barborough. A scar across his cheek and several livid weals on the back of his hands testified to his labours amongst the burning debris. Somewhat proudly Peter threw open the doors of the combined coach-house and stable. Within was a small governess cart and a sleek and obviously overfed donkey. "Allow me to introduce you to Butterfly," he announced. "Warranted to be quiet in harness and a thoroughly good trotter." Billy said not a word. He had contemplated with considerable misgivings the imposed task of driving a spirited mare through a populous district; but those doubts were as naught compared with the prospect of piloting a humble "moke" through traffic in a strange town. "Thank goodness I'm in mufti!" he soliloquised with a deep-drawn sigh. "'The condemned man walked firmly to the scaffold' sort of feeling. Well, here goes; no one is likely to know me in this show." Putting the animal into the shafts was an evolution that required the utmost tact on the part of Barcroft Senior and much nautical skill on the part of his son. It was their first attempt in this direction. "Get her this way while I hold the shafts," exclaimed Peter. "Gee up, old lady." Butterfly obeyed and took up a position athwart the hawse of the craft, as Billy expressed it. "Round with her," continued Barcroft Senior. "I can't hold these infernal shafts up all day." Putting his shoulders to the donkey's hind quarters Billy succeeded in "slewing the boat's stern round." "Easy astern!" he shouted in ringing nautical tones. Surprised beyond measure, Butterfly turned her head to take stock of this unusual type of groom, with the result that the flight-sub's face received a good buffet from the animal's nose. Simultaneously the brass trappings of the harness rasped Peter's hand.