This is book number 108 in the The Boxcar Children Mysteries series.
The Aldens are visiting Grandfather’s friend Abby in Peachland, Canada — home of the mysterious lake monster called Ogopogo. When the children learn that Abby must sell her resort unless she can attract more business, they decide to help. But someone or something is trying to get in their way. Can they save the resort?
The Boxcar Children Series was created by Gertrude Chandler Warner, a teacher, when she realized that there were few, if any, books for children that were both easy and fun to read. She drew on her own experiences in writing the mysteries. As a child, she had spent hours watching trains near her home, and often dreamed about what it would be like to live in a caboose or freight car. In each story, she chose a special setting and introduced unpredictable, unusual or eccentric characters, to help highlight the Aldens’ independence and resourcefulness. Miss Warner lived in Putnam, Massachusetts until her death in 1979.