Mike is taking a home movie of Jan and Cindy on the swings when Greg comes home with news of a history project. The project is a report on the early colonies that uses a creative method. Others have chosen plays, models, and paintings. Then Greg sees Mike's camera, and this gives him an idea for his own creativity - a movie about the Pilgrims at Plymouth. Later, as the parents settle down to bed, they express how pleased they are to see Greg so enthusiastic about history. They are less pleased to hear a typewriter at that hour and find it is Greg writing the screenplay for his movie. Mike is about to send Greg to bed, when he has an idea for the screenplay and starts typing himself. Alice overhears and starts joining in. Greg is not happy to see his parents and Alice taking over his screenplay. And this is only the beginning of an escalating problem of everyone monopolozing the project that he should be directing.
The props and scenery are well underway in the back yard. There is one mishap when Bobby gets stuck in the stocks. Carol proceeds with the costumes, but dresses Cindy in a pink patterned dress. Greg objects, saying Pilgrims wore black and white, but his parents do not listen. The girls fight over which of them should play Priscilla, and do not listen to Greg's protests that he should decide as he is director. Bobby and Peter insist on being Indians, not the Pilgrims Greg has cast them for, and they do not care that Greg is director either. Carol, Alice, and Mike all have their own ideas on how the hard winter should be portrayed. Eventually, Greg has had enough and tells his parents and Alice that he is sick of being out-directed by everyone. He wants to run the show his way because it is his project and he is the one who gets the grade - otherwise the movie is off.
This wakes the parents up and they apologize to Greg. They now agree to do things Greg's way and not interfere anymore. Mike will make sure the other kids will do things Greg's way too. New preparations go the way Greg wants, and smoothly. Shooting begins, but less smoothly. Mike is forced to intervene at one point because Greg forgot to take things off the lens. Jan plays Priscilla, and Bobby and Peter play both Pilgrims and Indians (but have to be told very firmly that they must be friendly Indians and not attack the fort). Alice bungles a costume change and is still wearing her John Carver mustache when dressed as a Pilgrim woman. Peter keeps misunderstanding normal conversation for his cues to produce snow with the snow box, and the cast want to break off for lunch. And during the shoot of the hard winter scene, the snow box suddenly stops producing snow because it has got stuck. Peter tips the box, and the entire contents get dumped on the Bradys.
But in the end the film is finished, and the family settle down to watch "Our Pilgrim Fathers, or Through Hardship to Freedom. Written, produced and directed by Gregory Brady." The film is a comical rendition of the Pilgrims' arrival at Plymouth and going through the Hard Winter, and the special effects make it even funnier. Everyone is rolling about with laughter.
Greg comes in and says he got an A for his project. The teacher did not think it was a great movie, but sure thought Greg showed how tough it was to be a Pilgrim. Later, Greg tells his parents that they are now doing the American Revolution, and he is full of ideas on how to shoot Paul Revere in the back yard. Mike jokes about what will happen next term, when they have to stage the whole Civil War.