NOTE: This spoiler was submitted by Jeremy.
Wendell Smith (Andre Holland) narrates that after the war, baseball became more prominent in the hearts of Americans. However, for African Americans, there was still much scrutiny and racism and Jim Crow laws being enforced. At the time, there were 400 white men playing baseball, but the number went down to 399 when one man stepped in and changed everything.
Branch Rickey (Harrison Ford) meets with Harold Parrott (T.R. Knight) and Clyde Sukeforth (Toby Huss) in the office of his Brooklyn baseball club, saying he wants to sign a black man to their team. Although Parrott says he will receive a lot of heat for this move, Rickey says there are as man black baseball fans as there are white. While going through their files, they come across one of Jackie Robinson.
We meet Jackie (Chadwick Boseman) with his own baseball club. While stopping to get gas for their bus, he tries to use the restroom, but the gas station attendant tells him he can't. Jackie says they'll get their gas elsewhere, so the attendant lets him go. When he steps out of the restroom, Jackie is met by Clyde.
Jackie meets with Rickey in his office, who offers him a chance to play for the Brooklyn Dodgers. Rickey tells him he must control his temper, because there will no doubt be people who will chastise him for being black. Jackie asks him if he wants a player who doesn't have guts to fight back, but Rickey says he prefers someone who wouldn't fight back. Jackie agrees to join as long as he can get a uniform and a number on his back.
Jackie calls his girlfriend Rachel (Nicole Beharie) in Pasadena. He proposes to her over the phone, and she accepts. He goes back home, and they are married.
In New Orleans, the couple prepares to fly to Florida. Rachel wants to use the restroom, but it's only available for whites. She goes in anyway, which is noticed by a lady working at the airport, and as a result, the Robinsons are not allowed to fly.
They make it to Florida on a bus and are met by Wendell, who is to be chronicling Jackie, and they stay at the home of a black couple, the Brocks.
It's the beginning of spring training as Jackie goes to play for the Montreal Royals. He meets Clay Hopper (Brett Cullen), manager of the Royals. During their first game, Jackie is met with cheers from the black crowd and boos from the white crowd. One black child watches him with awe. By the end of the game, one player on the opposing team drops the ball, giving his team the out.
During the game, Rachel feels sick. She goes to the bathroom where one woman suggests that she might be pregnant.
That evening, a white man approaches Wendell and Mr. Brock. He tells them that Jackie had best be getting out of there or else there will be trouble. Wendell tells Rickey about this, and he tells him to get Jackie out of there, but not to inform him of that issue.
Wendell takes Jackie out at night, and they pass a bar where a group of white men start walking near them. Panicked, Wendell drives out of there and almost hits another car. Jackie is told that they're avoiding more vitriol from the white men, but he laughs, saying he thought he was awoken because he was cut from the team.
During one game, Jackie is told by the sheriff to get off the field, and that he can't play, but Hopper goes to his defense. Jackie tells Rachel about it and appears to have a somewhat sardonic attitude about it. They are approached by a white man, who Jackie thinks is going to attack him and Rachel, but the man tells him he is supporting him all the way.
Sometime later, Jackie and Rachel become parents to a baby boy. While he watches him sleep, he tells the baby that he doesn't remember his father after he left him and his mother, but Jackie promises his son he will remember his father.
After spending two seasons with Montreal, Jackie makes it to the team and goes in for spring training, earning his uniform and the number 42. A bunch of his teammates start a petition to get Jackie off the team, and when their manager Leo Durocher (Christopher Meloni) hears about it, he angrily tells the players that if Jackie can help the team win, then he will play.
Durocher is caught in a scandal when it is discovered he is having an affair with an actress. He is suspended for a year, and the team is then managed by Burt Shotton (Max Gail).
During a game against the Phillies, their manager Ben Chapman (Alan Tudyk) constantly harasses Jackie by hurling racial slurs at him, egging him on. Jackie retreats to the dugout where he furiously smashes his bat against the wall and breaks down in tears. Rickey approaches him, saying that Chapman wants him to fight back. Jackie goes back out and is still insulted by Chapman, but he's defended by teammate Eddie Stanky (Jesse Luken).
Parrott angrily complains to Rickey about Chapman's behavior, but Rickey says Chapman is allowing Jackie to get sympathy with his rudeness. Although Chapman doesn't think he's doing anything wrong, since he uses slurs against Jewish and Italian players, he is told to change and then later poses in a magazine cover picture with Jackie.
Jackie becomes more popular, but he still has his detractors. The Dodgers He gets to Cincinnati and is booed at by the white crowd, to the point where a child yells slurs at him because his father is doing so. Jackie's teammate Pee Wee Reese (Lucas Black) stands next to him and puts his arm around him, receiving yells and boos from his usual fans. Pee Wee tells Jackie that perhaps they'll all be wearing the number 42 soon.
The Dodgers get to a game against the Pittsburgh Pirates, in which Jackie gets spiked up the leg and is seriously hurt. While he is treated, Rickey tells him that Jackie inspired him to love baseball again. He gets back out there and is faced with a pitcher, Fritz Ostermueller (Linc Hand), who beaned him earlier in another game. Jackie manages to hit a home run, taking the Dodgers to the World Series. Rachel is walking their baby as the neighborhood hears about this and cheers.
Wendell continues to write about Jackie and his accomplishments as Jackie triumphantly runs to home base.
The epilogue tells that Jackie, Branch Rickey, and Pee Wee Reese, among others, were inducted to the Baseball Hall of Fame at certain points. Wendell Smith was the first African American writer for the Baseball Writers Association of America. Ben Chapman was fired and never managed again. Dodgers player Dixie Walker, who was against Jackie, was traded to the Pittsburgh Pirates (as was another teammate earlier on).
The boy that Jackie tosses a ball to when boarding a train earlier in the film, turns out to be ED CHARLES who grows up and plays with the 1969 World Champion Mets, the Miracle Mets.
Every April, baseball players wear the number 42 on their Jerseys to commemorate Jackie Robinson's achievements. 42 is the only number retired from baseball.
Thanks for the update, Gordon