Hunter Crispian & The Little Brother of War by K.M. Topping

Fifteen year-old lacrosse player Hunter Crispian, his absurdly smart little sister, Tilly, and his quirky best friend, Chase are sailing to the Bahamas on a family vacation. "It will be the adventure of a lifetime," Hunter's dad promises. Talk about an understatement. Caught in a strange and sudden storm in the Bermuda Triangle, Mr. And Mrs. Crispian vanish into thin air and the three children are transported back to the year 1711, smack into the middle of a conflict between two Native American tribes. When the tribal chiefs declare a "Tewaarathon," or lacrosse game known as "Little Brother of War," Hunter and Chase soon learn that this will be no ordinary lacrosse game. In a contest without pads or helmets, rules or referees, the stakes are high. Win and the children shall go free. Lose and Hunter will die.