The Shooters (Presidential Agent 4)

Now, still in Argentina tying up loose ends from his investigation into the UN oil-for-food scandal, Castillo is startled when a young man is marched into his office at gunpoint, caught trying to sneak through the fence. It turns out he's an American officer, a lieutenant assigned to the embassy in Paraguay.

A key agent for the DEA has disappeared while trying to interdict drugs and very little is being done about it, for phony diplomatic reasons. The lieutenant's heard of Castillo, knows what he's done, and wants his help in getting the agent back. More than that, he's got an innovative plan for dealing with the drug lords themselves. Intrigued, Castillo gets permission to try it, but the President has just one warning for him: Don't get caught. Charley couldn't agree more-but it might turn out to be something easier said than done. . . .