Thirteen-year-olds Jonah and Chip are reeling from the news that they're both missing children from history, kidnapped from their proper time period. Before they can fully absorb this revelation, a time purist named JB zaps Chip and another boy, Alex, back to the fifteenth century, where they supposedly belong. Determined not to lose their friends, Jonah and his sister, Katherine, end up in the fifteenth century, where they decidedly do not belong.