(LOS ANGELES) — If you think you’ll know everything there is to know about Elton John after you see his upcoming biopic Rocketman, think again. The legendary star is also releasing a memoir this October called Me, and according to Taron Egerton, who plays Elton in Rocketman, it goes into way more detail than the movie possibly could.

“Our film is a two-hour structure so there’s a limit to how in-depth we can be,” Taron tells ABC Radio. “I’ve read Elton’s memoirs and they are incredibly brave and honest as he is. And yes, there’s a lot to learn about him, and I think people will be surprised at how candid it is.”

In fact, Taron got one of the earliest peeks at Elton’s memoir — the star allowed him to read it before he filmed Rocketman, so he could better prepare for the role.

“He very kindly gave me the chapters he had, it was unfinished at that point, so I had probably half of it, but it covered the time that we deal with in the film,” he explains. “And it was very, very enlightening.”

“A big theme in our movie is self-love and the perils of fame,” he adds. “And the movie begins and ends with Elton going to rehab, and he’s very candid about his history with substances. And that was very helpful for me.” 

While Taron got an early look at Elton’s memoir, Elton didn’t get the same for Rocketman: He’s chosen to see it for the first time when it debuts next week at the Cannes Film Festival.

Rocketman arrives in nearly 400 theaters nationwide on May 18; its official release date is May 31.  As for Me, that comes out October 15.

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