In the first episode, hosts Alice Roberts and Neil Oliver locate the origins of the Celts in the Alps of Central Europe, and relive the moment of first contact with the Romans in a pitched battle just north of Rome - a battle that the Celts won and devastated the city.

In episode two, Alice Roberts and Neil Oliver discover the golden age of the "La Tène" Celtic warrior and reveal how their world extended as far as Central Turkey. But by the middle of first century BC, the Celts were under threat from an expanding Roman Empire, and the Gallic warrior Vercingetorix would challenge Julius Caesar in an epic battle that would shape the future of Europe.

In the final episode, the Roman Army turns its attention to Britain, an island of rich resources, powerful tribes and druids, and advanced military equipment. We tell the story of the Celts last stand against the Roman Army, a revolt led by another great leader, the warrior Queen... Boudicca.