The former wife of infamous adventure author and thrill-seeker "Mad Buck" Gibson, hires Magnum to protect her ex-husband, who, despite being in later life, continues to live his life to the full as a hell-raiser. With Buck to stay as a guest of Robin Master's on the Estate, she wants Thomas to keep him out of danger until she has collected the back alimony money he owes, but he may not be around to pay it if he keeps on with his dangerous antics - something which is proven when Buck makes his entrance onto the scene in a dare-devil parachute stunt - injuring Higgins in the process! Thomas has his work cut out for him trying to ensure that the ageing adventure-seeker, determined not to let age get the better of him, doesn't come to any harm with his wild adventures, but as he does so, he discovers that the man is harbouring a worrying secret, and is seemingly set on a course of self destruction...