Higgins volunteers Magnum's services to guard a wealthy socialite's quarantined dog, after the attempted dognapping of the canine. "Sir Algernon Farnsworth" soon finds himself to be the most wanted dog in Hawaii, when his former owner, ageing gangster Victor DiGiorgio, has need to get him back. Magnum and an animal regulations officer are soon on the run with Algie from the would-be dognappers - and the fact that the officer seems to be scared of dogs doesn't exactly make matters any easier - but just why does DiGiorgio want the mutt back so badly?...