An Empty Coast by Tony Park. Sonja Kurtz Book 2

A body from an old war and a missing girl bring retired mercenary Sonja Kurtz home to Africa's deadly Skeleton Coast.

Sonja Kurtz former soldier, supposedly retired mercenary - is in Vietnam carrying out a personal revenge mission when her daughter sends a call for help.

Emma, a student archaeologist, on a dig at the edge of Namibias Etosha National Park has discovered a body dating back to the countrys liberation war of the 1980s.
The remains of the airman, identified as Hudson Brand, are a key piece of a puzzle that will reveal the location of a modern day buried treasure - a find people will kill for. Sonja returns to the country of her birth to find Emma, who since her call has gone missing.

Former CIA agent Hudson Brand is very much alive and is also drawn back to Namibia to finally solve a decades-old mystery whose clues are entombed in an empty corner of the desert.