Harry Banner turns up in London one November evening having just got back from Venezuela. He wants to see Robert Cade - a man he'd known six years earlier in Buenos Aires. He needs to ask him for a small favour just to keep a parcel until he calls back for it. The trouble is that Banner never does call back - the next morning he is found dead in his hotel room with a stab wound to his chest. Cade decides that a trip to Venezuela might throw some light onto the reasons for Harry's murder - but in San Borja, the climate can be very unhealthy for someone who asks too many questions.