SLINGSHOT

It is Christmas in Vietnam, 1968. Terrible heat and wilting humidity mark just another day.

At a desolate base camp in the northwest corner of the Mekong Delta, near the Cambodian border, a helicopter touches down and a stout little Hispanic man dressed coolly in khaki trousers and white shirt steps onto the ground. The military and political credentials of Mr.Mendez will prove to be unclear, which means he is CIA. Big shots rarely visit the camp at Tra Cu. It is home base for operations of...