Jimgrim by Talbot Mundy

Every tourist in the world knows what happened. While we were speeding toward Delhi in a 'plane provided for us by the Royal Air Force, McGowan and his staff were sending cablegrams in code to London giving a detailed explanation of Dorje's cypher, and London was distributing the information to all the governments of the civilized world through the embassies and legations, along with a careful description of Dorje's "thunderbolts" and the glass flasks containing his "death's breath."

Consequently tourists were exasperated by the questions they were forced to answer at every frontier they crossed, and by the minute inspection of their baggage. Droves of them were detained for special enquiries and were less annoyed by that than by the evasiveness and apparent indifference of their own ambassadors and consuls to whom they complained.