First half of film portrays life in port, including rum issue, distribution of letters, and taking on ammunition, the remainder tells the story of an action against German S-boats, in a stock-shot compilation including some captured film. Officers briefed; boats leave harbour, put to sea, "action", a Nazi naval flag is reclaimed from wreckage in the sea, and the motor torpedo boat (MTB) returns to port flying it below the British White Ensign. Film ends with a sequence showing the funeral of a Canadian seaman.