When a blind, retired dentist is run down by a logging truck as he crosses the road to post a letter, Dr Siri Paiboun, official and only coroner of Laos, finds himself faced with his most explosive case yet. The dentist's mortal remains aren't nearly as intriguing as the letter in his pocket. Written in invisible ink and encrypted, the letter presents Dr Siri with an irresistible challenge. Dr Siri soon finds himself on the trail of an international plot to overthrow the government.