Radius is a caring Roman: as a wedding anniversary present, he gives his wife Ulna a romantic cruise to take them gently to Lutetia, the city of light. It's an idyllic setting... except that there's nothing gentle about it: Asterix and Obelix, in a hurry to reach Lutetia in order to complete the legendary culinary bet made with Overanxius, transform the two lovers' ship into a speedboat propelled at top speed by Obelix, a truly avant-garde outboard fuelled by magic potion!
Ulna, who had warmly welcomed our Indomitable Gauls, is quite distressed by the whole affair! As for Asterix and Obelix, it's just as well they got a move on: it's in Lutetia that they'll meet a little white dog, as yet anonymous, who soon proves to be dogmatic in his desire to follow our two heroes!
In which book ?
5 - Asterix and the Banquet