The Secret Seven have stumbled upon another mystery without any intention to do so. Susie?s aeroplane is lost and they find it balancing on the second floor balcony of a house which is supposed to be empty. However, they realize that it could be possible that this house actually has occupants and is not empty as they, and everyone else, have been told.
Summary of the Book
The boys are jealous of Susie?s new aeroplane that has been given to her by her American cousin. It is beautiful and gleams under the sun. The children are bored in the beginning and don?t see a point in holding a Secret Seven meeting. They decide to take some of their picnic food and eat in the fields behind Jack?s house. Jack tries to show Susie how to fly the aeroplane, but instead the plane goes to the other end of the field and over a wall. They try to fetch it and see it balancing on the balcony of the house that is supposedly not occupied. With Jack keeping watch, Peter climbs the tree to get the plane. He takes a peek into the house, just in case, and is surprised to see that the gas fire is on and glowing. This has made him curious and Peter calls a meeting with the Secret Seven to investigate the Bartlett Lodge.