'Now don't change history while I'm gone', Mr. B had said before leaving Hannah and Nick to lock the trunk in the classroom closet. Despite Hannah's pledge to comply, a trickle of beach sand and a slosh of seawater turn to a flood tide after she lifts the lid. The siblings, along with their friend Jackie, find themselves in a wooden canoe off the seventeenth-century Texas coast - with a gale approaching and nothing to get them home but a magic ring and a list of riddles. No sooner does their rescuer, Sebastien, haul the trio aboard ship than they are pressed into service on the doomed French bark La Belle. Blamed for shipwreck, attacked on shore by arrow-firing Karankawa warriors, and chased by alligators, Hannah, Jackie, and Nick rush to complete the scavenger hunt with the aid of the settlement's resourceful colonists. From the Talon family they learn survival skills in the dense, dangerous woods - as they teach a few lessons of their own. But when a feverish Hannah collapses on the night of La Salle's long-awaited return, will a gold coin turn up in time to redeem her life?