River of Peril

In the fourth book in the series, Jem and his family are taking a trip to Sacramento and everyone is excited, especially Jem! But the whole trip he can't seem to kick the strangest feeling, and then their stagecoach is robbed and Jem's father doesn't seem to be upset about the robbery.

In Sacramento, Jem, his sister Ellie, and his cousin Nathan are enjoying the sites and tours when they come across a smuggling operation and Ellie disappears. It's up to Jem to use his wits and courage to find his sister before it's too late. . .