This film begins with the school burning down and there is a trial for arson against the girls (all of them!). They are found guilty but set free by the judge. The girls are taken on a ship, supposedly going to the Greek Isles. The ever lovelorn Sargeant Gates (the wonderful Joyce Grenfell) goes to meet up with them to see whats going on. She ends up on a desert island with Flash Harry (George Cole) and another man who has designs on her. Will they save the girls? Do they need saving? This film is not as good as the other two, since it deemphasizes the girls. Its a lot more of an adult film, they are much more prominent. Its not bad, just not quite as good. As for whether Sargeant Gates gets married..see the film. Its fine, just not essential unless you want to watch the series (all 4 films are available in a box set but unfortunately with no extras). So, check it out if you want to.