The Night Ranger by Alex Berenson

Ex-CIA agent John Wells knows the Middle East like the back of his hand. But now he's being thrown into an area he knows nothing about --Africa--at the request of the son he barely knows. Four aid workers from a Kenyan refugee camp have been kidnapped and no one is quite sure who's holding them or even whether they're still in Kenya or over the border in lawless Somalia. When John's estranged son calls him out of the blue asking him to help find the missing hostages, John doesn't hesitate. Soon he's in a land where he doesn't speak the language, has no contacts and is working without backup. The Night Ranger is quite the nail-biter. Sure, it does seem a little improbable that one man could pull off everything John Wells does. And yet, if you were in a similarly sticky situation, wouldn't it be nice to think someone that resourceful was on your side?