White Bone by Ridley Pearson

I love this series featuring big, burly former military contractor John Knox and petite, serious forensic accountant/computer whiz partner, Grace Chu. The two work for a company called Rutherford Risk that sends them out on, as you might suspect, risky missions involving things like hostages. In this case, Grace is sent to Africa to find out how a shipment of donated measles vaccine got switched with a cattle vaccine, making several patients very ill and forcing the closure of  an important medical clinic. Grace is making good progress on that front when she suddenly goes off the grid--and only Knox thinks something has happened to her. He heads off to Africa alone to try to track her down.

As it turns out, Grace has indeed been kidnapped--and left to die out in the bush. It takes all her skills and will to survive until help can arrive. John in the meantime is facing problems of his own, including a bogus murder rap. And then there's a subplot about poachers killing elephants for their ivory tusks -- the white bones of the title, which turns out to be intertwined with what Grace has uncovered. It's quite the page-turner and I can't wait for the next chapter in the adventures of this colorful duo.