The Thursday after Easter, Jesse receives a phone call from his music teacher, Miss Edmunds, who asks him if he would like to go to Washington D.C. with her to visit the National Gallery and the Smithsonian Museum. He says he would like to go and asks his sleeping mother for permission, knowing she doesn't comprehend what he is telling her. She gives a grunt for yes and he is off on his adventure.

Jesse is beyond happy traveling with the woman he loves to his first art museum. He hasn't been to Washington D.C. before, so this is a wonderful day for him. They explore the museum and eat at the National Gallery cafeteria, all new experiences for the boy. He doesn't think life can get any better than this day. As he goes through the day the constant thought in his mind is to tell Leslie about this day.

Miss Edmunds drops him back home later that day. Jesse comes in the door to the house happy as a lark, only to find his whole family, including his father sitting there; waiting for him. His mother cries out when she sees him, his father tries to comfort her. He learns a tragedy has taken place, Leslie is dead and his parents thought he perished with her.

She died swinging over the creek on the rope, which broke, causing her to hit her head on something and drown. Jesse can't take this news in, so he calls his Father a liar for telling him something so awful. Then he runs out the door and down the road, he runs because if he keeps on running, he thinks Leslie can't be dead. His father takes the truck and cuts him off, then he carries his broken boy back to the truck.

That night Jesse wakes up and thinks he dreamed that Leslie died, he convinces himself it is all just a nightmare. He does such a good job of persuading himself she is still alive, that he doesn't know who his father is referring to, when at breakfast, he speaks of the dead little girl. His father must tell him again of Leslie's death. Momma, Father, and Jesse go to Leslie's home to give their condolences to her parents.

Jesse and his parents walk to Leslie's house. Everyone is crying, except Jesse, he can't figure out why they are all crying. He then begins to consider his own reaction to Leslie's death. He realizes he will be important at school, because he is the first student to have their best friend die.

Bill, Leslie's dad, hugs Jesse and tells him she loved him. He also thanks Jesse for being such a good friend to his daughter. Then Bill tells Jesse's dad they are having Leslie cremated and returning her ashes to Pennsylvania, the next day. This is all too much for Jesse, he felt as if he was suffocating in the house, but finding out he will never see her again is the last straw for him. He runs away from the house. He can't understand how they can make all these decisions without consulting him, after all he is the only person on earth who really cared about Leslie.

He is angry she died, he blames her for leaving him alone in the world. He feels as if she opened up a new world for him and then left him alone.

He runs home to get the art supplies she gave him for Christmas, but on his way, he encounters May Belle, who asks if he saw Leslie's body. She receives a punch in the face for asking her question. He takes the art supplies to the creek and throws them in. His father finds him and comforts him, even telling him Leslie will not go to hell, no matter what May Belle says.

Later that day Bill brings the dog over, to ask Jesse if he will take care of him, while they travel to Pennsylvania. His mother lets the dog sleep on Jesse's bed with him.

Jesse woke up, the Saturday after Leslie died, with the desire to return his back to his normal life, which for him is milking the cow. Then he takes the dog and journeys back to the creek, where he finds a branch long enough to span the creek and strong enough to hold his weight. Back at Terabithia, he makes a wreath out of a branch and takes it to the grove, there he presents the wreath to the gods. He commands her spirit to them and feels Leslie's presence in the grove.

As he is done performing his ritual, he hears May Belle screaming for help. She is trying to cross the branch and is frozen with fear. He coaxes her down, then they return home together.

The next Monday at school, Jesse sees Leslie's desk has been removed from the classroom. His teacher sees how distraught he is and privately talks to him. She tells him she is also grieving the loss of Leslie and maybe they can help each other grieve.

Leslie's parents return to their house to pack up their things for the move back to Pennsylvania. Bill decides he needs to keep the dog, which is all right with Jesse. All Jesse asks for is some planks from the back porch. He takes them to the creek and builds a bridge- "the great bridge into Terabithia". He takes May Belle into Terabithia, telling her she is the new queen.

After spending the most perfect day of his life in Washington D.C. with Miss Edmunds, Jesse is given the worst news of his life. He finds out Leslie has died. He is at turns unbelieving of the news and angry at her for leaving him. His father shows compassion that Jesse didn't know he possessed. In the end, Jesse builds a bridge over the creek and continues going to Terabithia, with his sister as the new queen.