Top Secret was a videotaped crime series with filmed inserts set in Argentina. William Franklyn starred as British Intelligence operative Peter Dallas, who is granted a years leave of absence and returns to Argentina where he was brought up.

Back in South America, Dallas is engaged by wealthy businessman Migeul Garetta to act wherever the official forces of law and order can not. The adventures take place in both the cities and remote villages of the Argentinean pampas as Dallas becomes an independent crimebuster usually assisted by Garetta's nephew Mike. Using his abilities and experience from the world of espionage, Dallas becomes a formidable opponent for anyone daring to break the law.

In order to capture Argentina on film, a small unit under the control of director Ian Fordyce along with ex-paratrooper Franklyn spent eight weeks filming a mixture of establishing shots that would be used in the various episodes.

This series make Franklyn both a TV star and household name and led to his Schweppes - Shush, You Know Who! TV commercials.