Dana Shannon’s family buys a house which has been on Kansas Street for over a hundred years. The family was planning to renovate the house into a bed and breakfast inn. However, a mysterious discovery put the plans on hold. Dana was the only child and remained home to help her mum with the daily chores while dad was out to work. One morning, as Dana and her mum were scraping off the layers of wallpaper clinging on the walls, Dana had an idea that enabled her to dig a hole through the layer. After hitting a wood, Dana tried to push it to assess its thickness, but surprisingly it gave in. Inside was a full skeleton.
Back in April 1856, James’ family accommodated some Negro strangers. Millicent, James’ mother, warns the family against telling their names to protect her family from disclosing the identity of the strangers. These strangers help the Weavers with their family chores, but James discovers that the strangers are fugitive slaves on the run.
Dana and her mum call the police to help in unraveling the mystery. Police and doctors investigate the case and Dr. Baxi finds evidence that can be used to get information about the skeleton. After studying the bones for a while, the results show that the skeleton belonged to a Negro female aged between 130 and 140 years.
Some strange person came for Negro family at night to take them to their next destination. James and his little sister tried to inform their dad about shifting of the family in vain.
Dana discovered Millicent Weaver’s diary and does not tells anyone about it. Later she tells her parents about the diary and promises to hand it over to Dr. Baxi on the 1st of July.
When James’ father, Caleb, comes home, the mother brings up the topic of slavery. She asks for his opinion. Caleb agrees that slavery is wrong, but laments that it is illegal to help Negros. James spots some people uphill who appear like they were going for war. Marshall joins the town’s people who are engaged in a heated debate concerning slavery.
Dana got interested in reading Millicent’s diary. She learns from the diary that the house caught fire at some point. The town got attacked by people who came off the top of a mountain, firing a cannon ball that burnt the house. The Weavers buried some of their possessions in the yard.
Lizbet Charles visited the Weavers while Caleb was away. She had many fascinating stories making the children enjoy her company.
Dana was all alone at home when a tornado struck. At first she did not panic until she went down in the cellar, and a thought about Lizbet being in the same cellar came to her mind.
When Rebecca was sick, Dr. Oloney claimed he has made her feel better. However, Lizbet knew Rebecca’s well being was due to her wild indigo tea. Though a fierce storm was brewing, Lizbet had already made her mind on finding more slaves.
The grassland caught fire near James’ house. The neighbors assisted to put out the fire before it consumed James’ house.
Dana and her family go to California to visit her cousin. On their way back she gives her dad the diary to read. Dana discovers that James Weaver was the owner of the famous Wolcott castle right in their neighborhood.
Mother asked Lizbet not to go out in the storm, but she decided otherwise. Lizbet told Solomon not to marry before leaving. He was another slave staying at the Weavers’. Marshall suspected that the Weavers were helping the slaves and sent some men to closely spy on the house.
Dana realized that their new home was once an underground railway station. She also found out that the skeleton that has been hidden in their home belonged to Lizbet who worked as a conductor and was a slave. The reasons that led to her body being hidden in the secret location remain a mystery.