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 Namibia's Etosha National Park, has discovered a body dating back to the country's liberation war of the 1980s.

The remains of the airman, identified as former CIA agent 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.

But Hudson Brand is very much alive, and he is on a quest to solve a decades-old mystery whose clues are entombed in an empty corner of the desert.