M. Pinaud of the Surete is assigned to a Paris jeweler's shop to guard the Krontine diamonds which had once belonged to Russian royalty and now seem to have occasioned a murder- that of a watch repairman. In his surveillance of the gems, Pinaud also has time to speculate over the identity of the murderer, and he has four employees within the shop as well as several doubtful customers to choose from...In the formal tradition which takes its character from its detective, a man of infallible instincts and intuitions. Satisfactory.