A scientific expedition in the Atlantic Ocean becomes lost in the Bermuda Triangle and washes up on an uncharted island. They meet up with travellers from other times, planets and dimensions who have also become trapped, and together they "slide" through portals from one dimension to the next hoping to find the one that leads home.

The Fantastic Journey spawned a whole sub-genre of 1970s American science fiction TV. In each episode, a team of protagonists jump from one time zone to the next, encountering bizarre alien civilizations, pirates, the descendants of Atlantis, and even a 20th century funhouse of horrors.