The events of this true narrative chronicle the exploits of a top-secret mission carried out by the British military during World War II to destroy Nazi radio ships that were docked in a neutral harbor. Col. Lewis Pugh (Gregory Peck), a member of British Intelligence, and Captain Gavin Stewart, also a member of British Intelligence, are the men in charge of the audacious plot (Roger Moore). Due to the fact that the ships are located in neutral territory, the British military command must, despite their support of the plan, disavow any knowledge of it in the event that it is unsuccessful. Col. Bill Grice (played by David Niven), a retired officer, and some of his former soldiers are recruited by Pugh and Stewart to assist them. These allegedly inebriated old guys in civilian clothes must board three Nazi ships under the guise of a fishing expedition and destroy them since their radio transmissions have led to the destruction of allied ships by Nazi submarines. While Stewart organizes a distraction on land, Pugh and Grice carry out the risky raid on and destroy the Nazi ships. Stewart's job is to cover their tracks.