Atti is forced to join the Roman Army when one of his clever schemes falls foul of Emperor Nero. He is 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 rebellion, led by Boudicca. Atti rejoins his Roman troops and discovers they are preparing for an historic showdown with the Celts. Atti's brains could save the day, but they could also spell disaster for Orla as the two new friends find themselves lined up on opposite sides of the battlefield.