Invisibility Ray

The Invisibility Ray was a small prototype device created by the Nazis which allowed their agents to become invisible for short periods of time. Powered by a particular grade and a size of diamond for its lens, the ray was used for a series of diamond thefts from American museums, which also involved stealing electrical components, that had become known as the "Wraith Robberies" by a newspaper.

When four spies attempted to take the diamond from a museum connected to a group of adventurers, the adventurers moved to sabotage the device, or stop it from returning to Germany to prevent construction of the machine proper.

Behind the scenes
The Invisibilty Ray was created for an example scenario in Indiana Jones and the Rising Sun called Indiana Jones and the Invisibility Ray which was designed to assist gamesmastering for West End Games' The World of Indiana Jones roleplaying game.