[MR] A book recommendation request .. Roman period France.... suitable for an early teen

[Bruce Glassford]

Got posed this by my sister - and got stumped by it.   She and her family
(including my 11yo nephew) are heading to France this summer, and she wants
to get some books that cover France during the Roman time period - in either
French or English, primarily fiction, although non-fiction is possible.   I
hit a blank on it - my knowledge of books centered on that geographical area
tends to be for significantly later than the Romans, so anyone got
suggestions beyond Caesars Gallic Wars?

Thanks to all!

.... Bruce the potter