The cave at Mount Bonnell, not far from the school Hannah, Nick, and Jackie attend in Austin, has attracted many visitors over the years, from Indians to Boy Scouts to historic reenactors. But when Jackie's grandfather takes the trio there on an impromptu excursion, they meet a traveler of an entirely different sort: explorer Elijah Barrington, who has arrived there from the past. And accompanying him is a trunk that looks oddly familiar. A slam of the trunk's lid transports the girls into a melee of swirling hoofbeats and bright war paint. Before they know it, they've been taken captive by Comanche warriors in a raid on Victoria, Texas, in 1840. As they learn about life among the natives and participate reluctantly in another raid, Nick races east from Mount Bonnell on horseback in the company of Bigfoot Wallace, Jack Hays, and other Texas Rangers. As the old order of Texas clashes with the new at the Battle of Plum Creek, the youngsters find themselves on opposing sides—but also find friendship in unexpected places. Book Six in the award-winning time-travel series Mr. Barrington's Mysterious Trunk