Watch Full Series of Magnum, P.I. Online Full Episodes FREE in HD on 123movies. Download Magnum, P.I. Series 123movies new website. A private investigator who works when he wants, lives in a beachfront estate in Hawaii, drives a posh Ferrari, runs up an unlimited tab at a swank bar, and charms attractive women in peril - that's the lifestyle of Thomas Magnum, aka Magnum, P.I.