Guarda Streamingcommunity. When British Intelligence, following a series of experiments designed to increase alertness of long-distance lorry drivers through use of tonal repetition, discovers chordation that completely erases all memory, it is obvious that such a cleansed mind may be programmed to perform any type of action. Erstwhile agent Peter Clarke inactive for years, is chosen as courier to transport an audio tape of the tones to his native Australia.