kidnapped and is the girl pictured on the milk carton. But over and over again, she can't prove what she believes, or someone tries to talk her out of it. She begins to remember brief moments of her life before she came to be raised by Mr. and Mrs. Johnson. She remembers eating an ice cream sundae and someone telling her they were going for a ride. She remembers having a yellow dog. All of this leads Janie to believe that she really did have another life before the one she remembers with the Johnsons.

The climax comes when Janie and her boyfriend, Reeve, drive to New York and find the address of her birth family in the phone book, and she sees her siblings outside the house. Janie becomes more and more nervous as they drive closer to the house. She begins to ask Reeve what will happen if she tells the Spring family who she is, and she faces the frightening thought that the kind, loving, people she knows as her parents would be arrested for kidnapping. Finally, Janie and Reeve follow the school bus into the Springs' neighborhood. There they see children with red hair—just like Janie's—greeted by their red haired mother at the house, and Janie knows for sure that they are her family.

The resolution of the story comes after Janie accidentally loses the letter she wrote to the Springs, and she tells the Johnsons the whole story. Reeve's sister Lizzie helps her break the news to them. On the last page of the book, Mrs. Johnson calls the phone number for the Springs in New Jersey and hands the phone to Janie. Janie tells the woman who answers, "It's Jennie," ending the Springs search for their missing daughter.

The climax in The Face on the Milk Carton is the most important part of the action. It occurs in chapter 17 when Janie learns that the letter she had addressed to the Springs family has gone missing from her backpack. That letter had contained all the details and information that Janie had learned about her kidnapping and had also included her home address. Janie had not necessarily intended to mail the letter but had included all the essential details to avoid leaving any detail out.

These events then lead to the falling action of Lizzie explaining the details of the kidnapping to Janie's parents and relieving Janie of the heavy burden she had been carrying for so long. The family discusses how the Springs will react to the letter, and what Janie's plan of action should be. Janie and her parents share a tearful moment where they remind her that none of what has happened is her fault.

The resolution happens at the very end of the novel, and in a way is also the start to a new story which continues in the novel's sequel. It is triggered by a phone call from the Springs, which Janie answers and tells the woman on the other end of the phone that she is her daughter. It resolves the uncertainty that Janie had been dealing with throughout the entirety of the novel, of who her real parents are, and also suggests a resolution for the Springs as well, as they are about to learn what really happened to their missing daughter.

The climax occurs when Janie, who is shocked to see her own childhood picture on a milk carton, begins to recall events of her former life.  Eventually, "Janie confronts her parents and learns that she was left with them by their daughter Hannah. The Johnsons believe Hannah, who tells them Janie is their granddaughter, and that both Hannah and Janie are being pursued by a religious cult that Hannah joined when she ran away from home. When Hannah deserts the Johnsons and Janie, they take their granddaughter and flee their former life—moving to Connecticut, changing their last name from Javenson to Johnson— to avoid being discovered by the cult." 

There is no complete resolution to Cooney's novel.  Janie has to learn to live with new definitions of family, and what makes a family strong.  Her boyfriend, Reeve, helps her to do this but they both struggle with her emotional upheaval. 

I would argue that the climax of this book begins a chapter before the end, when Reeve's sister Lizzie explains everything to Mr and Mrs Johnson—that their daughter Hannah had in fact kidnapped Jennie Spring in New Jersey and passed her off as her own daughter.

After a debate about what the right course of action is, the family accepts that the Spring family needs to know what happened to their biological daughter. While they are discussing an option of Janie visiting the Spring family in exchange for no kidnapping charges being pressed, Mrs Johnson picks up the phone and dials the Spring's number. Janie then takes the receiver and speaks to her biological mother for the first time since the kidnapping that she does not remember.

The climax in the book takes place in chapter 17.  Janie places a summary of the details of her kidnapping in one of the envelopes she had typed her return address onto in typing class.  Later, "feeling spooky," she addresses the envelope to the Spring family.  On her way to her last class, Janie looks for the envelope and finds it is gone.  In a panic, she rushes to find Reeve so she can get his sister Lizzie's phone number.  At the end of the chapter we find out that she intends to have Lizzie call the Spring family before they receive her letter in the mail and call the police.