A banker, Mr. Alexander Holder of Streatham, makes a loan of 50,000 to a socially prominent client, who leaves the Beryl Coronet - one of the most valuable public possessions in existence - as collateral. Holder feels that he must not leave this rare and precious piece of jewellery in his personal safe at the bank, and so he takes it home with him to lock it up there. He is awakened in the night by a noise, enters his dressing room, and is horrified...