The following version of the book was used to create this study guide: Daughtry, Mikki. All This Time. Simon and Schuster Children's Publishing Division, New York, New York, 2020. Kindle AZW file.

The novel opens on the night of Kyle and Kimberly's high school graduation party. They have been a couple for years. On this night, as is too often the case, Kyle feels something is wrong. He bought Kimberly a custom charm bracelet with charms symbolizing events in the past and blank spaces to remind her of the future that lies ahead for them. When Kyle sees Kimberly talking to his best friend Sam, he knows he is not going to like what she has to say. Moment later, Kyle is shattered by the news that Kimberly has chosen a different college, specifically so that she and Kyle will not be together. She argues that she wants to know who she is without him and that Kyle should want that as well. She gets in his car, and he drives away. As the argument escalates, Kyle pulls over to give her the charm bracelet, hoping that will make Kimberly see they belong together. He sees a flash of lights as a truck hits them. He briefly wakes in the hospital and realizes the extent of of his injuries, especially the deep gash on his forehead.

When he wakes in the hospital, he learns that Kimberly is dead. Kyle spends most of his time in bed in his basement bedroom, avoiding everyone and feeling he will never love or have a life again. As he is forced to emerge a little, he decides to face one of his biggest fears by going to the cemetery. There, he meets a girl named Marley who is visiting the grave of her twin sister, Laura. Marley believes she is responsible for Laura's death. She cannot get past the grief.

Marley is grieving for Laura just as Kyle is grieving for Kimberly, and they connect over that shared experience. They soon begin to spend time together, usually at a local park where Marley loves to feed the ducks. Marley is a talented storyteller. She shares some of her writing with Kyle. Within months, the feelings between them deepen, and Kyle realizes he is in love with Marley. Sam is furious, saying Kyle is betraying Kimberly by moving on and pledging that he never will. Kyle comes to some important realizations, including that Sam loved Kimberly though Kyle has been too wrapped up in himself to see it. For the first time, Kyle sees that his relationship with Kimberly was not love. He had constantly tried to correct what was wrong between them without every stopping to understand why there was always something wrong. Kyle and Marley profess their love for each other and begin to settle into their lives. Kyle takes on a newspaper internship and begins taking college classes. Marley adopts a dog, and her grief begins to lessen.

Kyle takes a fall one night and wakes again in the hospital. This time, he learns he has been in a coma since the accident, which was only a few weeks earlier. Kimberly did not die, and no one knows Marley. Everyone tries to convince Kyle that his time with Marley was a dream, but he cannot accept it. One day, he sees Marley outside his hospital window and discovers she is the daughter of a nurse in the hospital. Marley, still in the depths of her grief for Laura, had read to him while he was in a coma. He remembered those stories, filling in details based on what he wanted. Kyle tells Kimberly she was right to want to break up, and he urges Sam to follow his own heart where Kimberly is concerned. Marley has not spoken since Laura's death, other than to read to Kyle. She also does not know Kyle the way he knows her, and she resists his attempts to connect. Finally, Kyle manages to connect with Marley. She begins to talk, first to Kyle and then to her mom. As Kyle begins to dream of a future with Marley, she is struck by a car and winds up in the hospital. When she does not wake, Kyle fears he has lost her again. Marley does awaken, saying she had taken this opportunity to say good-bye to Laura and is now ready to move forward with her life.