A middle grade time travel Arianna's family are proud new owners of a souvenir shop on Mackinac Island - the perfect place to make money for her paraplegic brother's surgery. No motor vehicles are allowed on the island, but there are plenty of horses easily avoided, making the island safe enough for Luc to have mobile freedom in his wheelchair all summer long. When Arianna and Luc accidentally discover that a powder horn that's been in their family for generations can send them back to 1793, they meet their great-great-great-great-great-grandfather, the person who carved the treasure map on the powder horn. How can the siblings convince their ancestor to let them in on its secrets? After all, they are family. To complicate matters, Luc finds he can walk there, back in the past. He doesn't want to return to the present where the surgery is uncertain, and a wheelchair may be his life. Arianna must choose between discovering the family treasure and bringing and keeping her brother in the present.