Following this prologue, Chief Vitalstatistix is made helpless by a sore liver, a consequence of overeating and drinking at his last banquet.

Having demonstrated this, and temporarily eased the chief's pain, the druid Getafix sends Vitalstatistix to a hydrotherapeutic center in Arverne to be cured, with Asterix and Obelix (and Dogmatix) as his escort.

At Arverne, the Gauls initially remain together; but because Asterix, Obelix, and Dogmatix are in no need of special diets, they feast on wild boar and beer while everyone else eats "boiled vegetables".

To that end, they interrogate the archer, Lucius Circumbendibus, who now owns a wheel manufacturing business; the second legionary, Marcus Carniverus, who worked at a health resort before opening a restaurant; and the drunken Centurion Crapulus.

Upon the protagonists' reunion with him, Winesanspirix confesses having given the shield to a dispirited Gaulish warrior, who is thereupon identified with the arrival of a newly cured and much slimmer Vitalstatistix.