The sea-wind in his hair, his eyes agleam with the fresh memory of Alpine snows, Will Warburton sprang out of the cab, paid the driver a double fare, flung on to his shoulder a heavy bag and ran up, two steps at a stride, to a flat on the fourth floor of the many-tenanted building hard by Chelsea Bridge. His rat-tat-tat brought to the door a thin yellow face, cautious in espial, through the narrow opening.