Three months ago, in a wind battered tent clinging precariously to the snow-clad slopes of a mountain in Butan, a letter was written. Tonight in a hotel in China, a telephone rings. The connection between them? Well recently there has been talk of the enemy developing a specific tropical disease to use as biological warfare. Since then, a scientist who specializes in tropical disease has gone missing, so naturally Ken Thurston wants to get to the bottom of the case, and find out where and why he vanished.