Notes: This is #11 in the long-running non-SF series about the tough U.S. government assassin and counteragent Matt Helm. It concerns his investigation of a flying saucer hoax in Mexico -- but, on the very last page, an apparently real UFO makes a brief but inconsequential appearance. On the spine of the book, reading from left to right, is: "A Fawcett Gold Medal Book THE MENACERS Donald Hamilton 231-01980-060". In the very upper left of the front cover, as if hanging down from the top of the cover, is the small Gold Medal Book insignia. Inside it is: R1989, and then, below that, 60c.