Nimoy died at the age of 83 in February 2015 and Adam had to not only grieve, but figure out what direction he wanted his film to take. He eventually turned it into a love letter to the man who millions knew simply as Mr. Spock.
"My stepmother [Susan Bay], said I needed to include my own perspective, my own story, my own journey with my dad," Nimoy continued, "which had a lot of ups and downs, but ended on a good note. We thought it was a story worth telling to make the film unique."
Even Nimoy himself, 59, said he learned things about his father from directing the picture. So, without further ado, here is what you may not know about Spock, Leonard and "Star Trek," as told by Adam and others in his touching film.
Leonard's Parents Were Against Him Acting
The film explains that his parents grew up during the Great Depression and were "grief stricken" when he told them he wanted to study drama.
Leonard Focused on His Career When Adam and Julie Were Young
Julie was also featured in the doc and said he would often sleep on his couch on the set and never turned down appearances, because he didn't want to see his family struggle.
He also really took the role of Spock seriously, his children said. He would come home, eat and run lines with his wife. But being Spock, he wasn't the warmest father. He was quiet and remote, Julie added.
Spock Was Created With Nimoy in Mind
He thought he was auditioning for the original "Star Trek" series in the 1960's, but he realized that the creator was actually "selling" him on taking the job.
Nimoy added in the film that prior to "Star Trek," he never had a job that lasted longer than two weeks.
The First "Star Trek" Pilot Was a Failure
No Color TV
The night of the "Star Trek" premiere in September 1966, Adam said he had to go watch at a friend's house, because the Nimoys didn't have a color TV back then.
Nimoy's View of Spock
He watched him perform and how he just stood there with his hands at his sides. But when he made any gesture, the crowd lost its minds. That really got Nimoy's attention.
The Vulcan Grip
This was Nimoy's idea. Originally, he was supposed to hit Captain Kirk with the butt of a gun, but Nimoy thought they needed something better. Shatner sold the move and the rest is cinematic history.
The Vulcan Greeting
Nimoy spent his childhood going to synagogue for the High Holidays and he saw some of the symbols used during the chants, including one with the hands. It was in the shape of the Hebrew letter for Shin. That ended up being what he went with and within days of the series airing on TV, Nimoy said fans started using the greeting with him on the street.
Nimoy didn't know "Star Trek" was going to be such a hit, so his address and number were published. Big mistake. Trucks had to come eventually, Adam said, delivering loads of letters and fans would stop by the house to see if they could meet Leonard or take a souvenir.
Diversity Important to Leonard
"It says a lot about Leonard," Takei said on the doc.
"Star Trek: The Motion Picture"
Nimoy said a check arrived at the house and a script an hour later.
At first, producers tried to talk Nimoy out of directing "Star Trek 3," but with its success, he directed the next one.
His children say "Star Trek: The Voyage Home" was one of the heights of his career. Then came "Three Men and a Baby."
A Low Point
After Nimoy directed "The Good Mother" in 1988, it was a box office failure, and at the same time, Adam said their relationship hit an all-time low. Leonard's parents also passed around that time and he went through his divorce with his first wife, Sandra.
"He was also drinking and I was getting high at the time," Adam said.
After marrying Susan in 1989, Leonard kept drinking and realized he needed to seek recovery for his alcoholism. He started drinking on the set of the original series and admitted it slowly got worse and worse over time. Eventually, Adam would seek his own recovery, he said in the film.
The Rebirth of "Star Trek"
Adam said working with J.J. Abrams was yet another high point in his life, as the famed director rebooted the series in a new direction.
Abrams shared a personal story in the documentary, where Leonard fell while filming and broke his nose.
"When you've wounded Spock you want to kill yourself," he said. But Nimoy wanted to keep shooting.
"Is he out of his f----- mind, he just broke his nose," Abrams said.
Adam and Leonard
After being estranged years earlier, Adam and Leonard reconnected in 2008 and started to talk again. After Adam's wife Martha was diagnosed with terminal cancer, the first phone call he made was to his dad.
"It overwhelms me now that we could get to that point," Adam said. "After that, my dad and I never looked back at wreckage from the past."
Leonard Died a Family Man
The movie ends with how happy the movie icon was being with his family. He said he used to major in career and minor in family. That changed before he passed on Feb. 27, 2015.
For more information or movie times and where you can see "For the Love of Spock," visit the website at FortheLoveofSpock.com.