It’s a work 10 years in the making–two-time Pultizer Prize winning author Robert Caro released his fourth biography on Lyndon Johnson this month.

"The Passage of Power" has flown off the shelves at area book stores.

“Some folks were commenting that it’s been about 10 years since the third volume, ‘Master of the Senate,’” Book People Manager Bryan Sansone said. “And folks have been waiting quite a while to get that in their hands.”

The staff at Book People in Downtown Austin say the first 25 copies of "The Passage of Power," signed by the author, flew off the shelves and sales have stayed steady since its May 1 release.

“I’ve always been interested in LBJ. I think he’s the most interesting and well, after FDR, the most important president of the 21st century,” Book People customer Tom Hackett said. “He tells a really good story, so I’ve been wanting to dive in, but I’m afraid it’s a huge undertaking.”

Roughly 3,500 pages, Caro’s latest book is his fourth volume depicting Johnson’s rise to power and what he did once he arrived in the country’s top seat.

“He did the right thing, but he also knew how to twist arms to do it. He wasn’t just a do-gooder. He was a do-gooder who was willing to use whatever means necessary to accomplish good,” Hackett said.

Robert Caro plans to publish a fifth volume of the "The Years of Lyndon Johnson." No word yet on when the last installment will be released.