The Menagerie

TOS Season 1 Episode 11 and 12
Air Date: November 17th and 24th, 1966

When Gene Roddenberry first approached NBC with Star Trek and he made a pilot where Captain Christopher Pike was the main character on the Enterprise. NBC didn't like the pilot saying that they felt the Pike wasn't the right character. So Roddenberry went back and did a second pilot with William Shattner as Captain Kirk "Where no man has gone before" which became the 3rd episode of the series.

But instead of throwing away the footage he re-cut it into a two part episode where Captain Christopher Pike was seriously wounded and living his life as a vegetable but with an active mind. Much like ALS but a much longer lifespan. Spock hijacks the Enterprise with the goal of bringing Captain Pike back to Talos IV, a forbidden planet with aliens that can implant illusions into your mind.

I won't get into the contents of the pilot as I will watch it when I get to the late 80s when it was officially released, but the parts specific to the episode were around Spock being tried for mutiny and threatened with the death penalty. The trial has footage of Captain Pike going to Talos IV, from an angle that no camera could have seen. Turns out they were all illusions that were used to get Captain Pike to Talos IV where he could live a life in an illusion instead of the painful reality he was living.