The lifelong feud between Max (Walter Matthau) and John (Jack Lemmon) has cooled. Their children, Melanie (Daryl Hannah) and Jacob (Kevin Pollak), have become engaged after a brief relationship. Meanwhile, John is enjoying his marriage to wife Ariel (Ann-Margret).

The spring and summer fishing season is in full swing in Wabasha, Minnesota, with the annual quest to catch “Catfish Hunter”, the lake’s largest catfish, consuming the fishing community. However, the local bait shop closed after the death of its proprietor Chuck in the first film. New arrival to Wabasha, Maria Ragetti (Sophia Loren), has purchased the building with the intent of converting it into a fancy Italian restaurant. Max and John join forces to try to sabotage the restaurant and are successful.