Carmen Elcira narrowed her eyes and studied his face. He was wearing the plainest of clothes, with sunglasses propped on his head.

I have two devices to me solve mysteries like that: a camera with a macro lens, and a pair of surgeon's glasses, which are heavy metal frames with little binocular telescopes mounted on them.

A pair of 3-d glasses like those that helped the film shatter box office records will be included with the issue of the magazine which hits US newsstands on Friday.