The hemisphere of heaven was drenched in moonlight, and—­rare happening either on British earth or on the waters surrounding it, in mid-summer—­the night was warm.  In the midst of the glittering sea the yacht moved without the appearance of motion; only by leaning over the rail and watching the bubbles glide away from her could you detect her progress.  There were no waves, no ripples, nothing but a scarcely perceptible swell.  The gentle breeze, unnoticeable on deck, was abaft; all the sails had been lowered and stowed except the large square sail bent on a yard to the mainmast and never used except with such a wind.  The Ariadne had a strong flood tide under her, and her 200-h.p. twin motors were stopped.  Hence there was no tremor in the ship and no odour of paraffin in the nostrils of those who chanced to wander aft of the engine-room.  The deck awning had been rolled up to the centre, and at the four corners of its frame had been hung four temporary electric lights within Chinese lanterns.  A radiance ascended from the saloon skylight; the windows of the deck-house blazed as usual, but the deck-house was empty; a very subdued glow indicated where the binnacle was.  And, answering these signs of existence, could be distinguished the red and green lights of steamers, the firm rays of lighthouses, and the red or white warnings of gas-buoys run by clockwork.

The figures of men and women—­the women in pale gowns, the men in blue-and-white—­lounged or strolled on the spotless deck which unseen hands swabbed and stoned every morning at 6 o’clock; and among these figures passed the figure of a steward with a salver, staying them with flagons, comforting them with the finest exotic fruit.  Occasionally the huge square sail gave an idle flap.  “Get that lead out, ’Orace,” commanded a grim voice from the wheel.  A splash followed, as a man straddled himself over the starboard bow, swung a weighted line to and fro and threw it from him.  “Four.”  Another splash.  “Four.”  Another splash.  “Four.”  Another splash.  “Three-half.”  Another splash.  “Three-half.”  Another splash.  “Three.”  Another splash.  “Two-half.”  Another splash.  “Three.”  Another splash.  “Five.”  “That’ll do, ’Orace,” came the voice from the wheel.  Then an entranced silence.

The scene had the air of being ideal.  And yet it was not.  Something lacked.  That something was the owner.  The owner lay indisposed in the sacred owner’s cabin.  And this was a pity because a dance had been planned for that night.  It might have taken place without the owner, but the strains of the gramophone and especially the shuffling of feet on the deck would have disturbed him.  True, he had sent up word by Doctor Cromarty that he was not to be considered.  But the doctor had delivered the message without any conviction, and the unanimous decision was that the owner must, at all costs, be considered.