The series starred Gregory Harrison as Logan 5 (the title character), Heather Menzies as Jessica 6, and Randy Powell as Francis 7.

The series maintains the basic premise and visual style of the film in that Logan and Jessica have escaped from the "City of Domes" so that they will not have to die upon reaching the age of 30.

The series differs from the plot of the movie in various ways, and depicts Logan and Jessica on the run in each episode in various locations on future Earth as they search for the mythical place known as "Sanctuary".

Logan and Jessica are also assisted in each episode by an android called REM (acronym for Reclective – meaning self-programming, problem-solving – Entity Mobile), a character created for the series and played by Donald Moffat.

Logan and Jessica were joined on their journey by an android named Rem (played by Donald Moffat), whom they encounter in a futuristic city run by robots.

In a 2017 interview, Heather Menzies stated that Dirk Benedict and her Sound of Music co-star Nicholas Hammond also auditioned for the role of Logan 5.

75-minute pilot episode: In the 23rd century, survivors of a nuclear war live in a domed city where they are allowed to stay alive only until age 30.

Logan is a Sandman who's begun to question the system, and he and a woman named Jessica leave the city to seek a mysterious place called Sanctuary, pursued by a trio of Sandmen led by Francis.

Logan and Jessica are abducted by John the Protector and Joanna, aliens from another planet who are manipulating their minds, making them believe that they have found Sanctuary.

Logan, Jessica and Rem are attacked by two bands of duplicate humans with vastly different temperaments: one group is kind and gentle while the other is violent and vicious.

The Runners are captured by scientists of an authoritarian, concealed city who plan to use Logan in their experiments to remove all human fears and to create a powerful army.