If you loved Go Tell the Spartans, try Beneath the Planet of the Apes
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Ted Post, and they both carry the dread mood tag. If that's the register that drew you to Go Tell the Spartans, the second film will land in a comparable space — through a different lens.
dread
What Beneath the Planet of the Apes is
A desert landscape, scorching sun, a spaceship crash. A lone survivor stumbles upon an ape metropolis, ancient ruins hidden beneath. This sequel descends into darker terrain.

