A Chinese spy ring is operating in Singapore and Drake is sent to infiltrate, taking the place of a man already working for the ring, in order to try and bring the ring to an end.

There's a nice Portuguese villa where an English lady and her husband reside.  Lodger's there are suspected when the husband disappears and Drake is assigned to see what's going on.  He is brought in on a smuggling ring by the lodgers who say they are smuggling industrial diamonds.  In reality, they are smuggling missile electronics.