John ""The Baron"" Mannering and his lovely wife Lorna accept an invitation to attend a large exhibition of precious stones and objects d'art from an old friend, Raymond Li Chen in Hong Kong. Their ""second honeymoon"" takes on a funereal air as Mannering becomes deluged by threatening notes, phone calls etc. and John himself is tapped as an off-the-cuff investigator for Scotland Yard. There are hints of an immense smuggling operation; a cat and mouse game between Formosa and Peking. Forced into disguise, Mannering finally finds himself looking at the largest collection of invaluable objects ever garnered. It might be his last look....A ready audience...a puzzlement.