Dorothy Dunnett 
Split Code [PDF ebook] 
Dolly and the Nanny Bird

Joanna Emerson, a trained nursery nurse, is hired as a nanny, albeit reluctantly, to the infant heir of a cosmetics fortune. She then becomes caught up in a complex kidnap plot. She is also an expert in codes and her purpose is to gain an insight into the opposition plan? But how does kidnapping further anyone’s interests? Commencing in Winnipeg, Manitoba, the story moves quickly through locations, as with many of Dunnett’s stories. On this occasion Joanna ends up on a crippled yacht off the coast of Yugoslavia. As always, both behind and aside from the plot and it’s inevitable conclusion is enigmatic portrait painter, yachtsman and former spy, Johnson Johnson. Bullets are flying, most of them in Joanna’s direction. Just how can this end?