Audiobook: Thief

At a dinner party, a valuable coin is lost while being passed around among the guests to look at. One of the gentlemen insists to empty his pockets to the host to free himself of all suspicion, and the other gentlemen concur, except one, who absolutely refuses, and leaves the house. Is he the thief or did he have another reason to wish to avoid inspection of his pockets? - Summary by Carolin