Atti is a Roman teenager with brains but very little brawn. When one of his schemes falls foul of Emperor Nero, Atti is forced to join the army and sent to miserable, cold, wet Britain. Things go from bad to worse when Atti is captured by Orla, a feisty teenage Celt desperate to prove herself as a warrior. Meanwhile a furious Nero is determined to crush the British rebellion, led by Boudicca. As the Romans prepare for an historic showdown with the Celts at the Battle of Watling Street the two new friends find themselves lined up on opposite sides of the battlefield.