Gus Was a Friendly Ghost is a thirty-two page children's picture book that was first published in the United States in 1961. The text is credited to Jane Thayer, a pseudonym often used by the prolific American author Catherine Wooley. The illustrations are by Seymour Fleishman.
The book concerns a ghost named Gus who simply wants everybody to be happy. He haunts an old house that is the summer home of the Scott family. Even though he does not have any direct contact with the Scotts, Gus is very fond of them and he misses them very much when they leave in the autumn. Gus' loneliness leads him to step outside the house to take a walk. He then meets a mouse who complains of being cold. Gus invites the mouse to stay with him. The mouse accepts the invitation after Gus reassures him that there are no people in the house. The mouse hates people. When the Scotts eventually return, the mouse does not want to share his home with them and that causes problems.
Eight more books about Gus the ghost were written and were first published between 1966 and 1989.
The old house in the country where Mr. and Mrs. Scott and their twin children Phoebe and Sammy spend their summers is also home to a ghost named Gus. Although he never has any direct interaction with them, Gus likes the Scotts very much. While the Scotts are at home, Gus stays in the attic. He rattles chains and makes other noises because he believes that is what people expect a ghost to do. Even though they do not believe in ghosts, the Scotts jokingly comment, "We've got a ghost", when they hear the sounds Gus makes.
At the start of the autumn, the Scotts leave their summer house. Gus is left entirely on his own. He does not make the sounds anymore because there are no people in the house to hear them. Gus feels very lonely. To cheer himself up, he goes out for a walk. He comes across a mouse who is suffering because of the cold weather. Gus invites Mouse back to his house for the winter. Since Mouse hates people, he is somewhat reluctant to go back to the house at first. Gus reassures Mouse that the house is completely free of people.
Gus is able to magically start a fire in the fireplace to keep Mouse warm and magically produce cheese for Mouse to eat. Unable to sleep on any of the beds because they are covered in newspapers, something that he hates, and unable to sleep in any of the drawers because they have mothballs in them, Mouse follows Gus' advice and goes up to the attic to sleep. He makes himself comfortable inside an old mattress.
Gus provides Mouse with three meals a day and snacks. He learns to cook many different cheese-based recipes. Mouse never helps him. At night, Gus and Mouse sit next to the fire. Sometimes they make popcorn. Sometimes they play checkers. The light from the fire shines through the window and smoke comes out of the chimney. Nobody ever sees that, however, because no people ever go near the house.
The weather becomes warmer and the Scotts come back to their summer house. Mouse is not happy because Gus cannot cook for him anymore and simply because he hates people. He decides to frighten the Scotts away. He goes inside the walls and runs about. The Scotts hear him and realize that they have a mouse, although they are not frightened away. Afterwards, Mouse nibbles at some of the Scotts' food and intentionally spills more food on the floor. He chews a hole in a pillow. While the Scotts are in bed, Mouse goes up to the attic and then tries to make as much noise as he possibly can.
Mr. Scott sets a trap for Mouse. Finding the cheese on the mousetrap almost impossible to resist, Mouse almost gets caught in it. Gus is able to stop him and puts a warning sign up in front of the trap. Mr. Scott sets more mousetraps. Gus puts warning signs up in front of each of them. At the same time, Mouse carries on trying to frighten away the Scotts by being as noisy as he can be. All of this upsets Gus. He does not want Mouse to come to any harm nor does he want the Scotts to be bothered.
Mouse then succeeds in scaring Mrs. Scott when he shows himself to her on a kitchen shelf. This proves too much for Gus to take. He angrily tells Mouse that he can only stay in the house if he agrees to follow certain rules. Gus says that Mouse can never frighten Mrs. Scott again. He also has to stop nibbling and chewing the Scotts' food and belongings. He can go outside and eat seeds instead. Finally, Gus says that Mouse has to be quiet at all times. The frightened Mouse agrees to follow all of the rules. Gus feels bad for having scared his friend. In a kindly voice, he adds that Mouse only has to follow the rules until the autumn when the Scotts will leave again.
Not being able to hear Mouse anymore, the Scotts assume that he has gone and the mousetraps are removed. The Scotts hear the sounds that Gus makes coming from the attic once again and are happy to do so.
Autumn comes once more and the Scotts leave the house again. Gus and Mouse celebrate the start of their winter together with cheese croquettes for dinner.