Currently available on 3 streaming services.

Streaming, rent, or buy Magnum, P.I. – Season 4:

You are able to buy "Magnum, P.I. - Season 4" on Apple TV, Amazon Video, Microsoft Store as download.

Cast

Tom Selleck
Thomas Magnum
John Hillerman
Jonathan Higgins
Roger E. Mosley
Terry "TC" Calvin
Larry Manetti
Rick Wright