Henry, Jessie, Violet, and Benny used to live alone in a boxcar. Now they have a home with their grandfather, and they are going to be on the radio! The Alden children are helping out at a radio station, and they're going to be actors in a live mystery show. Benny is especially excited—he gets to play the part of the ghost dog! But it seems the ghost dog might not be the only spook at the station. When strange things keep happening, people in town say the station is haunted! Can the Boxcar children catch the radio ghost before the station's listeners are scared away?