How do you sell an old-fashioned hero story?

That’s the challenge Warner Bros. and Legendary Pictures are facing with Jackie Robinson biopic “42,” touting it as “The true story of an American legend.” They’re using the arrival of the Major League Baseball season as a launching pad — virtually ensuring that the core audience of baseball fans know that “42” opens April 12, three days before the 66th anniversary of Robinson’s major league debut in 1947.

The numerical title is Robinson’s uniform number — which the MLB retired for all teams in 1997 to mark the 50-year anniversary of Robinson’s first game. The drama, directed by Brian Helgeland and starring Chadwick Boseman as the pioneer in breaking the MLB color barrier, is also aiming far beyond baseball enthusiasts.

It’s a strategy that Warners used effectively four years ago when “The Blind Side” — ostensibly a football story, but actually a family drama — became a breakout hit. Sony was also able to expand the audience impressively in 2011 with inside-baseball tale “Moneyball” with $110 million worldwide.

“With sports dramas, it has be about much more than sports if it’s going to work,” notes longtime Disney studio chief Dick Cook. “The stakes have to be higher than just than the mere game. You already know how the story ends but you don’t know the steps to getting there.”

Cook, a member of the Legendary board, came on to the project at the behest of Legendary topper and “42” producer Thomas Tull. Cook’s an executive producer on “42” with the experience of having seen success in sports dramas with “Remember the Titans,” “The Rookie” and “Glory Road.” He helped arrange meetings with Robinson’s widow Rachel and with Ralph Branca, the last surviving member of the 1947 Brooklyn Dodgers.

So Warners and Legendary have been aggressive in promoting Helgeland’s movie as covering far more than bunts, beanballs and baserunning with more than 100 screenings in recent months. The faith-based community has been a target, given the film’s themes of brotherhood, redemption, the joys of marriage and the liberal use of Biblical quotations by Harrison Ford’s gruff Branch Rickey character.

The Jackie Robinson Foundation has been tub-thumping “42” through its scholars and alumni at 87 colleges and universities. And Boseman has been on the talk-show/interview circuit nonstop in recent weeks.

The campaign has stressed Robinson overcoming the era’s blatant racism thanks to his relationships with Rachel Robinson (Nicole Behaire), Rickey and his Dodger teammates, particularly Peewee Reese (Lucas Black) and Branca (Hamish Linklater).

That’s very much in line with Helgeland’s vision.

“It’s very important to capture the action on the field, which is why we used a lot of Division I college players, and the look and feel of the era,” he told Variety. “But for the story to really work, it had concentrate on those three relationships.”

Robinson’s career as a Brooklyn Dodger lasted a decade and landed him in baseball Hall of Fame. But the film largely sticks to the 1947 campaign and offers career recaps only in the end credits. Helgeland, who grew up as a Boston Red Sox fan, also believed it was crucial to compress the time period covered by the movie — a point that he admitted required some persuasion for Rachel Robinson to endorse the script.

“I think that the more time you covered for Jackie, the less drama the film would have,” he notes.

Sports movies are historically a tough sell — particularly overseas, even if they succeed domestically. Only one baseball movie has ever toppped $100 milliion in domestic grosses: 1992’s comedy-drama “A League of Their Own,” which took in $107 million for Sony.

No doubt energizing Warner’s hopes for the pic finding broader appeal, a trio of recent sports pics earned critical acclaim, kudos and strong box office: The David O. Russell-helmed “The Fighter” took in $130 million and two Oscars; John Lee Hancock’s “The Blind Side” topped $300 million and won a best actress Oscar for Sandra Bullock; Bennett Miller’s “Moneyball” received a dozen Oscar noms and grossed $110 million worldwide.

Curiously, there already is a Robinson biopic — 1950’s “The Jackie Robinson Story,” in which Robinson portrayed himself. In 2004, Marc Turtletaub and David Friendly had planned a Robinson film with Robert Redford as Rickey;  Philip Anschutz, who helped finance 2005’s Ray Charles biopic “Ray,” had attempted to develop a Robinson movie around the same time but those projects never gained traction. Legendary began working with Rachel Robinson about two years ago.

Nine-year-old Legendary is best known for financing and producing big-budget high-profile projects like the Batman films, “Inception,” “Man of Steel” and the “300” and “Hangover” franchises. But early on, Legendary ventured into the arena in 2006’s inspirational sports drama “We Are Marshall,” which grossed $43 million.

Cook is brimming with enthusiasm for “42,” asserting Helgeland overcame the challenges of narrowing down the story and getting the baseball action right.

“Nothing takes you out of a sports movie faster than seeing something not looking authentic,” he added. “What Brian has done is way beyond our expectations.”

Alcon Entertainment co-topper Andrew Kosove, who produced “The Blind Side,” is a already a big fan of “42.”

“It took real courage on the part of Legendary to make a film like ‘42,’” he said. “There are large parts of the world that don’t follow or participate in baseball. It’s also a historical, period piece, and those kind of films are never easy to sell. However, the upside is that one has the chance to uplift people by reminding them of the best qualities of the human spirit. Legendary Pictures and Brian Helgeland have made a great, inspiring film. We not only are rooting for the movie to succeed, but we are also expecting that it will succeed.”

Top grossing baseball movies since 1989 —

Title, domestic gross, year of release

1. A League of Their Own, $107.5 million, 1992

2. Moneyball, $75.6 million, 2011

3. The Rookie, $75.6 million, 2002

4. Field of Dreams, $64.4 million, 1989

5. The Benchwarmers, $59.8 million, 2006

Source: Box Office Mojo