David Hughes's book The Greatest Science Fiction Movies Never Made
has a chapter about Star Trek, but spends a paltry two pages discussing Kaufman's version, which is a shame, since much of the rest of the chapter is padding about the films that ultimately were made and only one other (Starfleet Academy) that wasn't. My guess is he didn't have any luck getting his hands on any substantial materials related to the project.
I'll summarize what the book says.
After being interviewed by Roddenberry, who liked their take on Captain Kirk, Chris Bryant and Allan G. Scott (who wrote the ultra-creepy Donald Sutherland vehicle Don't Look Now
) wrote a treatment for a story called Planet of the Titans
, which was delivered in October 1976. As they started working on the script, Kaufman was hired. Kaufman said, "I liked Star Trek because I felt it dealt with mature, adult themes..."
Bryant and Scott found themselves caught between Roddenberry and Kaufman's conflicting ideas of what the film should be, and Paramount's not really knowing what they wanted. Feeling it was "physically impossible" to produce a script that satisfied all parties, they left the project by mutual consent in April 1977. "We begged to be fired."
Kaufman took on the task of writing the script.
The Greatest Sci-Fi Movies Never Made wrote:
Kaufman said "My version was really built around Leonard Nimoy as Spock and Toshiro Mifune as his Klingon nemesis...My idea was to make it less 'cult-ish', and more of an adult movie, dealing with sexuality and wonders rather than oddness; a big science fiction movie, filled with all kinds of questions, particularly about the nature of Spock's [duality]—exploring his humanity and what humanness was. To have Spock and Mifune's character tripping out in outer space. I'm sure the fans would have been upset, but I felt it could really open up a new type of science fiction."
According to the book, on May 8th, 1977, the morning he felt he'd finally cracked the story, Jeff Katzenberg called with the bad news that Paramount had decided to pull the plug...three weeks before Star Wars came out.
Susan Sackett summarizes the plot of the submitted script in "The Making of Star Trek: The Motion Picture
". Again, I can't speak to the accuracy of her summary, but here it is in a nutshell; prior to being lightly edited by various hacks for inclusion in various fan press books.
Susan Sackett wrote:
The Making of Star Trek- The Motion Picture, Chapter 3: Sub-Warp Speed p.32–33
Their story opens with the Enterprise racing to rescue the Da Vinci, a Federation ship in trouble. They arrive too late—the Da Vinci has vanished—but they pick up survivors. During the rescue Kirk is subjected to an electrochemical shock to his brain which brings on erratic behavior culminating in his commandeering a shuttle craft toward an invisible planet. He vanishes without a trace and Spock orders the Enterprise home.
Three years later, the Enterprise, refitted, has a new crew. Spock has resigned from Starfleet in disgrace and is on Vulcan purging himself of his human half (a recurrent theme in all scripts, it would seem). The Enterprise, under Captain Gregory Westlake, is ordered to the place where Kirk disappeared. Just as Spock theorized, a planet has been discovered, one that promises to be the mythical "planet of the Titans," the home of a lost race with super technology. The planet is about to be swallowed up into a black hole. Whoever rescues the Titans—Klingons or the Federation—will control the destiny of the universe. The Enterprise makes a detour to Vulcan to pick up Spock, who at first refuses to go, but during his tests on that planet Spock has his own death revealed to him, indicating that he must go with the Enterprise in order to fulfill his destiny. The Enterprise arrives at the now partially visible planet and is trapped by the force fields surrounding it. Facing certain destruction, the Enterprise saucer separates from the Star Drive, allowing the Star Drive to get free, while the saucer crash lands on the planet. The crew finds the surface of the planet to be a wild and inhospitable place with cities encased in walls of fire. Spock is reunited with Kirk, who has existed as a wild man on the planet with other trapped beings. When the landing party finally reaches the rulers of the planet they find they are not the benevolent Titans, but a lower and incredibly dangerous and intelligent life form—the Cygnans. The Titans have long disappeared. In the attempt to escape from the Cygnans, who have transported on board before the ship lifted off and rejoined the Star Drive, Kirk plunges the Enterprise into the black hole to save the Federation from the Cygnans. During the trip through the black hole, the Cygnans are destroyed, and the Enterprise emerges back in orbit around Earth. But it is Earth at the time of the Cro-Magnon man, the dawn of humanity. The ancient Titans, it would seem, were the men of the Enterprise!
I would hazard a guess that the invisible planet is hidden within the "shroud" in McQuarrie's renderings. I'm also guessing the Enterprise
saucer might've landed on Vulcan to collect Spock and
been caught within the shroud/landed on the titular planet.