In this Doc Savage story that spans a few generations, we find out why Doc doesn't age-he's invented an immortal elixir from a rare plant and has tested it on both himself and his female cousin, Pat, before revealing it to the United States government in the 1960's. But a bad guy, who owns pharmaceutical companies, doesn't want this cure for age and disease-and blows up Doc's island facility, the only place this miraculous plant grows.
The following stories follow Doc and his crew to the present day and it's a decent update of the original novels. Recommended.