The New York Public Library is moving forward with a $300 million renovation to its midtown campus. It's the second time plans have been announced for the landmark research library at 42nd street and the Mid-Manhattan circulating branch across Fifth Avenue. But library leaders say, this time, it's a different story.

Under Bryant Park, workers are building out a new acre and a half of climate-controlled storage for books. The additional level of subterranean shelves will house millions of volumes from the library's collection. Dusty rooms in the majestic central building will be restored, opening 42 percent more space to the public.  The 1970s-era, Mid-Manhattan circulating library across the street will be gut renovated and transformed into what library officials say will be a model for other branches in the system, which spans Manhattan, Staten Island and the Bronx. Eventually, the functions of the Science, Industry and Business Library will move to the circulating library, too, and its space on 34th Street will be sold. It's all part of what New York Public Library president Tony Marx calls "the largest renovation in our history."

And it's a sequel. Eight years ago, the library had a different proposal, named the Central Library Plan. It called for selling off the Mid-Manhattan property and moving its operations to the ornate research library, now named the Stephen A. Schwarzman Building. To make room, the building's historic stacks, which library officials said were outdated and threatening the collection, would be demolished. And millions of books were sent offsite to storage, sparking outrage from writers, scholars and local leaders.

"I was quite frankly stunned," said author Annalyn Swan. "When you go into a library, it’s like a breadcrumb trail. One book leads to another. And the thought to me that that would be taken away and books taken off site was simply unacceptable and unimaginable."

New Yorkers tend to feel a deep connection to the library, a sense of ownership. But despite its name, it’s a nonprofit, funded through both public and private dollars — a structure that dates back to its founding. And it's overseen by a Board of Trustees, which mostly appoints its own members. When news of the Central Library Plan broke, critics accused that board of secrecy and shortsightedness.

"The Central Library Plan was an attempt to consolidate and to save money but there wasn’t enough thought given to the integrity of the 42nd Street library or the fact that the Mid-Manhattan library, though in a decrepit state, is a beautiful library at the crossroads of a great city," said Nation contributor Scott Sherman, author of a recent book about the controversial plan, Patience and Fortitude: Power, Real Estate and the Fight to Save a Public Library.

He said a lack of transparency caused "tremendous mistakes" to be made. There were petitions, op-eds, hearings and protests. Preservationists said demolishing the stacks threatened the library’s literal and figurative foundation. Then mayoral candidate Bill de Blasio said the plan for the Mid-Manhattan Library would be part of a pattern in the Bloomberg administration of selling off public space.

Once in office, the de Blasio administration pushed for changes. And the library dropped the Central Library Plan and went back to the drawing board, seeking input along the way. New architects chosen in September are working on designs based on that guidance. The Mid-Manhattan Library won't be sold, but overhauled, with an adult learning center, new computer labs, advanced shelving systems, and a more welcoming first floor. In the Schwarzman Building, the old stacks are staying and will be used as swing space while the Mid-Manhattan Library is renovated and the collections are digitized. With thousands of new shelves under Bryant Park, officials say the books will be back from storage in six months and 95 percent of requests will be met within half an hour.

Local leaders who opposed the plan say they support this one. "In general, the library listened," said Manhattan Borough President Gale Brewer. "To me that's most important."

But some researchers aren't satisfied. They say the library wasted millions of dollars on the previous plan, money that could have gone to address key capital needs throughout the system. They worry the shelves under Bryant Park won't be able to fit as many books. And they'd prefer to see the books return to the stacks. "I feel the glass is half empty," says Swan. "Why can't you retrofit the stacks as other major institutions have done?"

But Marx says that would be too expensive: retrofitting the stacks would cost $47 million, compared to $23 million to build out the space under Bryant Park. And Marx adds that the current plan will protect the books, preserve the central library's role as a research institution, and provide the funds to upgrade the circulating branch — all while saving money to enhance services.

"We heard their concerns, we did our homework, the trustees re-examined the issue and said 'There's another way to do this, let's do it that way because that's what we owe the public,'" he said.