Led by Julius Caesar, Rome has just invaded Britain. Cordelia, the Queen of the Britons, sends her trusty officer Anticlimax to seek help in Gaul, in another little village famed for its dogged resistance to the Romans...

Meanwhile, Asterix and Obelix have been entrusted with a delicate mission - to make a man of Justforkix, the Chief's devil-may-care nephew who thinks of nothing but girls and music. But when Anticlimax finds our two heroes and describes the desperate situation facing the Britons, Asterix and Obelix accompany him to the fight with Justforkix in tow.