Navy Instructional film discussing potential threats to a ship in harbour and demonstrating the precautions necessary for ships entering port under threat of terrorist or covert attack. The briefings and preparations for 'Awkward State 3' are shown, including searches of the jetty and the establishment of a perimeter around it in order to control access to the ship. Underwater searches by divers are also shown. The film is set on the Type 21 frigate HMS Alacrity (F.174) in company with an unidentified Rover Class Royal Fleet Auxiliary ship and an unidentified O Class submarine. The Type 42 destroyer HMS Edinburgh (D.97) also appears.