NOTE: This spoiler was submitted by Alex
Jeff Bauman (Jake Gyllenhaal) is an average man who lives in Boston and works at Costco. After work, he’s getting drinks with some of his friends when Erin (Tatiana Maslany), his ex-girlfriend, enters the bar getting donations for her Boston Marathon Run to support the hospital where she works. She’s just recently broken things off with Jeff, and he rallies the whole bar to donate. He tells her he’ll see her at the marathon she doesn’t believe him since he’s always been terrible at showing up. He promises to be there.
Jeff lives with his mother, Patty (Miranda Richardson). She is an excessive drinker, but she loves Jeff dearly. Jeff makes a sign for Erin and goes to the Marathon. Erin is in the middle of the race when the explosions go off. She makes it to a phone and is able to call her sister to tell her she’s alright. She sees a photo of Jeff as one of the victims on the news and is shocked.
Patty and Jeff’s father Big Jeff (Clancy Brown) arrive at the hospital. The doctors tell them that Jeff is alive, but that most of his legs needed to be amputated. Erin and Jeff’s family wait for the outcome of the surgery. Jeff’s boss from Costco, Kevin, arrives and is harassed by Jeff’s big Boston family for firing Jeff but he explains that Jeff isn’t fired, he’s just dropping off all the insurance information.
Jeff finally wakes after his surgery. He asks for paper and writes, “Is Erin okay?” The next thing he writes is, “I Saw the Bomber.” Erin stays with Jeff while his breathing tube is removed so he can talk to the FBI. One of the bombers is killed, and the other captured. Jeff becomes a local hero, the face of the “Boston Strong” movement in the wake of the attacks but he isn’t entirely comfortable with that, and doesn’t feel like a hero at all.
Jeff is finally released from the hospital Patty’s place is on a high floor of an apartment with only stairs, so Jeff has to be carried up in his wheelchair. His family is having a big welcome home party for him, but he just asks Erin to help him into the bathroom so he can take a shower alone. Jeff’s adjustment to having no legs is difficult, often falling and hurting himself, drinking a lot, and going in and out of depression. His family encourages him to meet with Carlos, the man who saved his life in the bombing, but he refuses.
The Bruins ask him to come out at their game with the flag as a showing of Boston Strong. Jeff doesn’t want to but agrees because his family wants him to. His one ask is that Erin come out onto the ice with him. She’s the only one who isn’t sure if he should be doing it. He tells her he knows it’s not fair to ask her because they technically aren’t together but he needs her. She agrees. At the game, Erin wheels Jeff out. He waves the flag, but the crowd and the noise are overwhelming once they are off the ice his PTSD is triggered, and he screams at Erin in the elevator to “help someone else.”
Erin and Jeff sleep together for the first time since the bombing. They become incredibly close Erin quits her job to be a part of Jeff’s rehabilitation and physical therapy. Jeff asks Erin to move in with him, and she accepts as long as he tells his mother. At a Bauman family cookout, Erin mentions she’s moving in, and Patty is annoyed that no one told her. Patty announces that Oprah is flying out to interview Jeff. Erin tells Patty that Jeff doesn’t want to do any more interviews and that it’s too stressful for him, but Patty ignores her and tells Jeff to say it to her face. Jeff finally admits he doesn’t want to do it.
Erin takes a pregnancy test, and it comes out positive. Meanwhile, Jeff is still struggling with his physical therapy and his status as a hero to the people of Boston. He’s depressed and drinking more even drunk driving with his friends. Erin comes home and finds him, and Patty both passed out, Jeff covered in vomit. The next day Patty and Jeff don’t wake up in time to get to physical therapy, so Erin hustles them there. Jeff isn’t trying all that hard, and his doctors tell him he needs to push himself and practice and not miss any more appointments if he truly wants to improve. Afterwards, Erin and Jeff argue over whether Jeff is trying Erin is upset he doesn’t acknowledge how people have made their lives revolving around him. Patty gets involved, screaming at Erin that she’s not helpful and getting very personal - it becomes a massive shouting match, and Erin leaves.
Erin asks Jeff to meet her for dinner so she can tell him that she’s pregnant. He’s out at a bar with friends and ignores Erin’s texts. When a patron at the bar recognizes Jeff and says that the Boston bombing was faked by Obama to invade Iran, Jeff and his buddies get into a brawl with Jeff screaming for someone to hit him. Erin picks him up, insulted and hurt. She gives Jeff the card telling him he’s going to be a father. He tells her he can’t do it; How is he supposed to run after a kid, he can’t deal with this right now. Erin tells Jeff she’s given up her job and everything for him, she’s not giving up this too. Jeff maintains he can’t be a father, and Erin tells him it’s not because of his legs, it’s because of him. He’s a big kid, and their child will be another person he won’t show up for. Jeff screams at Erin “I SHOWED UP FOR YOU!” implying it’s her fault that he’s lost his legs. Erin leaves and runs up to the apartment to pack her things. Jeff falls out of the car and crawls to the apartment door, begging Erin to let him in. He begins having PTSD flashbacks to the explosion, and we see the actual carnage of the bombing for the first time. Carlos (Carlos Sanz), a civilian, rescues him and gets him to safety Jeff is screaming “help someone else.”
Jeff finally agrees to meet with Carlos. Jeff asks why Carlos was at the marathon, and he tells him he was there in support of his two sons, both of whom died. One in the military, and the other of suicide after his older brother died. He tells Jeff that he reminds him of his younger son and that helping him was like helping his son, and thanks, Jeff. Jeff can’t believe he’s thanking him since he’s the one who should be doing the thanking. Meeting with Carlos gives Jeff a better sense of perspective.
Jeff and Carlos go to a Red Sox game where Jeff throws out the first pitch. After the game, Jeff is mobbed by fans. Where before Jeff would resent the attention, now he listens as a young man tells him how his brother died in Iraq, and how Jeff’s perseverance reminds him that they can’t be broken. Jeff talks with dozens of people who he’s inspired and is kind and patient.
Patty drops Jeff off at the restaurant where he stood up Erin prior. She’s waiting inside to talk with him. He gets out of the car on his prosthetic legs and walks, carefully, inside. Erin watches him finally moving on his new legs. He tells her he loves her. “Good,” she says.
Closing words on the screen say that the Red Sox won the world series that year, Jeff and Erin’s daughter was born, and years later, Erin finally completed the Boston Marathon. Jeff was waiting for her at the finish line.