Again and again I went over the whole circumstances as they had been related to me. There was, I reflected, one circumstance common to all three of the robberies, if robberies they were. There had been at the time some unusual amount of confusion, all lending opportunity for a theft to take place without immediate detection. The Dowager Lady A.’s diamonds had been stolen during her illness, or about the time of her death. The Countess of B. had lost her diamonds during the excitement of a wedding breakfast at an hotel. At Colonel C.’s house, there had been a ball on the night when the bracelet was lost. Was there any one, I asked myself, who, by chance or intention, had been present at each place at the time of the robbery? Any occasional waiter, for example, or servant of any kind? I could not find that there had been. Yet, if the thief were not one of the household, how was it that a stranger should in three separate instances fix on an establishment where the circumstances were favourable to a robbery of valuable property? In two cases, there had been illness and a hasty summoning of doctors. That led to another thought: was it possible that some experienced thief or gang of thieves had laid themselves out to track the broughams of fashionable West-end physicians, on the chance of finding hall doors left open, and property somewhat loosely guarded? I had not thought of such a thing seriously before; but it seemed now to be an idea worth following up. Once more I resumed inquiries. Who was the doctor summoned in the case of the Dowager Lady A.? I easily ascertained. It was one of the best known men, at that time, in London. He and his brougham would be familiar to every thief who frequented West-end thoroughfares. I next inquired at Colonel C.’s. To my satisfaction, I learnt that the same doctor had attended in this case. ‘Here,’ I said to myself, ‘I begin to see daylight.’ Shortly afterwards, I made a further discovery. The coachman who drove the famous physician to Lady A.’s on the night of the accident, and to Colonel C.’s on the night of the ball, had only been in his employ a few weeks; and on the date of the Earl of B.’s wedding, the man had driven the carriage of one of the guests at the breakfast. The clue I felt was becoming strong. The thief, I grew convinced, was a confederate of the grave-faced man in spotless black who drove the fashionable doctor from one house of sickness to another. I resolved to obtain an interview with the doctor, and after explaining my suspicions, plan some mode of detecting so consummate a rascal. Circumstances occurred to make me resolve to carry out my purpose without delay.