This book is about three children.The three of them were Bobbie,Peter,Phyllis.They were very lucky because they had everything that they needed.Suddenly,there was a big changed for them.At Peter's ten years old birthday,they were three people came to them house and tell something to they parents.The end of the birthday is sad but Peter to got a toy steam engine.It quickly became Peter favourite toy.The next day morning,they mother tell them they will moving in a dear little white house near a railway line.They changed poor.The house not had light ang they have to got some coal.They mother don't allow ther used the coal fast so they they going to stealing the coal on the hill.The station Master caught them but he not do anything to them.They know an old gentleman at the station so an old gentle man said hi to them everyday when he pass the station.Sometime they wrote each other and they were celebrate birthday for each other.One day the three children were walking by the fance along the top of the hill beside the railway line. They saw the tree moving slowly downwards on the opposite side of the railway line.It was danger and it will make lots of people die so they saving the tarin.At last,they do it.One day,Bobbie found a newspaper.It was a trrible secret in the newspaper.They daddy was a spy.She was so amazing for it.She mother tell her daddy not a spy.It someone to frame up he so Bobbie wrote to an old gentleman to found the real spy.