"A woman driver, of course" had been Dr. Richard Guyse's impatient inwardcomment as he braked and swerved to avoid a collission with the open cardoor of the unknown but attractive young girl. He wondered briefly who shewas and then promptly forgot her. That was a trick of mind training on whichDoctor Guyse prided himself. He could always switch his concentration to theimportant details of his busy doctor's life - yesterday's operation, today'sX-ray, tomorrow's problemetical new case - the exclusion of everything else.Doctor Guyse did not know it then, but his meeting with Lysbet Marlowe wasthe beginning of a strange disturbance in the powers of concentration.