"I would say even to get to be part of something where Clint Eastwood and Leo DiCaprio and Naomi Watts are a part of it, like, I'll be 5th, 6th, 7th, 8th fiddle," said Hammer.
But in "J. Edgar," he's is a lot more than "8th fiddle." Hammer co-stars as Clyde Tolson, the longtime friend, colleague and possibly love interest of the infamous FBI director, played by Leonardo DiCaprio.
Hammer has an unusual tie to the story: his great grandfather, Armand Hammer, spent time in Hoover's crosshairs.
"I was familiar a little bit with J. Edgar's infamy because, I guess, he had a grudge against my great grandfather. He was one of the guys he went after, or something like that, so going through the trash, people following him, phone tapping, that kind of thing," recalled Hammer. "I heard those stories growing up, so when I picked up the script and read it for the first time it wasn't really like, 'wow, he did all this, this and this?" It was like, 'oh wow, that was true? Interesting.'
"But then getting to work on the project you see sort of the very fragile and damaged human side of him as well, which was good to see."
Hoover was an incredibly private person. Eastwood and screenwriter Dustin Lance Black did exhaustive research into the man's life both personally and professionally.
The story told in this film shows Hoover and Tolson shared a deep intimacy with one another and with their jobs.
"It's a tragic sort of love story between these two guys and also it's a tragic love story between Edgar and his bureau," said Hammer.
"J. Edgar" opens in theaters Friday, November 10.