Originally published in the U.S. by Popular Library as "Countertrap" in 1967. This Italian edition is number 217 in the (then) weekly "Segretissimo" series published by Arnoldo Mondadori Editore on 25th January 1968. John Tiger was a pseudonym of Walter Wager, used for adaptations of the TV series "I-Spy." Cover art by Carlo Jacono.