A British spy trawler is sunk in the Aegean Sea. Oceanographer Jack Hedley ("Havelock") is tasked with trying to find the ship before a vital piece of tracking hardware falls into enemy hands. Things don't go to plan though, and once the wreck has been located a brutal murder ensues and Roger Moore ("007"), aided by the daughter of the murdered scientist (Carole Bouquet), has to try and track downver mais...