The Coworker

Caleb hands Dawn an all-white sandwich and gleefully describes watching Natalie being arrested. He announces that they must leave because Natalie has traced a call back to the motel. Dawn admits that she could not resist making the calls. She enjoyed taunting Natalie, just as Caleb did when he placed the turtle figurine on Natalie’s desk. Caleb remarks on the coincidence that a woman was found dead just as Dawn went missing. The woman’s body was not immediately identifiable because she was so severely beaten and all of her teeth were missing. However, Caleb points out that the police will eventually discover that the body is not Dawn’s.

Caleb has the video of Natalie’s arrest on his phone. The two rewatch it together before having sex. Dawn is infuriated by Natalie’s claim that the fun run is in honor of Amelia. She has written a letter to Mia describing how she and Caleb framed Natalie. Dawn views her coworker’s imprisonment as justice, since Natalie got away with killing Mia years ago.

The narrative flashes back to Dawn’s early childhood and school years and focuses on her friend, Amelia. During this time, Amelia’s friends called her Mia. Born with cerebral palsy, she walked with crutches and was self-conscious about her slurred speech. Dawn bonded with Mia in the first grade, and they looked out for each other throughout their school years. Once, Dawn pushed a boy named Jared Kelahan off the monkey bars when he made fun of her friend. Likewise, when another boy taunted Dawn, Mia threw water over his pants and claimed that he had wet himself. However, when Dawn left for college, Mia had to face the cruelty of other high school children alone.

Natalie Farrell and her best friend, Tara Wilkes, bullied Mia incessantly. The girls mimicked Mia’s voice in classes and encouraged other classmates to join in. When Mia complained, teachers refused to believe her, asserting that Natalie and Tara were incapable of such bad behavior. Mia had a crush on a boy named George and started to receive romantic notes from him. Consequently, when she saw George with a red rose on Valentine’s Day, Mia assumed that it was for her. After George explained that the flower was for another girl, it emerged that Natalie and Tara had written the romantic notes. Humiliated, Mia took her own life.

Devastated by Mia’s death, Dawn was determined to make Natalie pay for her actions. One day, she saw Mia’s brother, Caleb, and discovered he shared her hatred of Natalie. When Dawn started working at Vixed, Natalie did not recognize her as a former classmate.

Natalie cannot afford a lawyer and accepts free legal assistance. Her attorney reveals that the prosecution has amassed significant evidence against her. Dawn’s emails describe how Natalie bullied her and how she discovered that Natalie was stealing from Vixed. Dawn’s blood and hair were also found in the trunk of Natalie’s car. Furthermore, Caleb voluntarily retracted Natalie’s alibi and claimed that she asked him to leave at 9:30 pm on the night of Dawn’s disappearance. The only good news for Natalie is that DNA testing has shown that the body found in the woods is not Dawn’s.

Natalie’s attorney disbelieves her insistent assertions that she is innocent. He advises her that she is likely to face life imprisonment unless she confesses and accepts a plea bargain. Natalie decides that if a lifetime in prison seems probable, she will throw herself into the sea at Wollaston Beach. Remembering how Amelia ended her life at high school, she suddenly realizes how the girl must have felt.

The narrative relates aspects of Caleb’s past. Caleb was devoted to his half sister, Mia. A mutual desire to take revenge on Natalie fueled his friendship with Dawn, and they fell in love. Dawn intended for the police to find the emails that she wrote to Mia in the months preceding her staged disappearance. Caleb replied to these emails, pretending to be his half sister.

Dawn is troubled by Caleb’s fake romance with Natalie and accuses him of enjoying the act of kissing her. Caleb denies this, reminding her that he did not want to date Natalie and only did so at Dawn’s insistence.

Natalie is terrified during her first night in jail. She shares a cold cell with an aggressive-looking woman who takes her blanket.

Dawn and Caleb move to another unpleasant motel. Checking the news, they discover that the police now know that the dead body is not Dawn’s. Dawn worries that Natalie may not be convicted without a body.

Natalie’s parents call her in jail. Natalie’s mother assumes that her daughter is guilty and reminds Natalie of her misdeeds from her high school days, particularly her act of bullying a girl who died by suicide as a result of the abuse. Natalie’s mother asserts that Natalie will have to face the consequences of her actions. Natalie feels that her mother’s judgment is unfair, for she has tried to atone for the past by organizing charity runs.

While Caleb is asleep, Dawn finds an engagement ring box in his pocket. However, she struggles to believe that Caleb loves her. Dawn concludes that she needs to be dead for her plan to work.

Natalie is astonished when Seth pays her bail. He drives Natalie home and apologizes, revealing that he has checked the accounts and now knows that she did not steal money from Vixed.

Natalie receives a message from Caleb claiming that he checked the motel but found nothing useful. Seth reveals that Caleb knew Dawn before he started working at Vixed; she was the one who recommended him for the website job. Hearing this, Natalie realizes that Caleb had opportunities to plant the incriminating evidence in her house and car.

Natalie resolves to check out the Rhode Island motel herself, and Seth offers to drive her there.

At the motel, the receptionist recognizes a photo of Caleb and confirms that he checked out with a woman on Saturday. Natalie finds Caleb waiting on the doorstep when she returns home.

Caleb admits to planting evidence to incriminate Natalie. He explains that Amelia was his sister and Dawn’s best friend. Caleb also reveals that Dawn is not dead, but she has recently gone missing. He asks for Natalie’s help in finding her. He fears that she intends to drown herself in order to produce an incriminating body.

Caleb, Seth, and Natalie split up, heading for three different beaches. Natalie goes to Wollaston Beach, where she previously disposed of the ceramic turtle. Approaching the pier, she sees Dawn.

Dawn believes that the best part of her life is over. She will never have another friend like Mia or be in love again. With a cinderblock tied to her ankle, she waits to jump into the ocean at high tide. Dawn is confident that once her body is found, Natalie will serve a life sentence for her apparent murder.

Recalling that her own actions were always more extreme than Mia’s, Dawn wonders if her friend would have made a similar sacrifice. For example, Mia once said that Dawn had gone “too far” when she pushed Jared Kelahan off the monkey bars. Dawn also remembers how a teacher screamed when she saw the pool of blood surrounding Jared. Dawn is just about to jump when she sees Natalie approaching. Natalie urges her not to jump, pointing out that Dawn’s death would be futile since Caleb has admitted everything. Furious, Dawn decides to kill Natalie instead.

Dawn raises the cinderblock above her head, accusing Natalie of killing her best friend and stealing the man she loves. Natalie grabs the mace from her bag and sprays it in Dawn’s eyes. Dropping the cinderblock, Dawn falls to her knees. Natalie claims that she has always regretted what she did to Amelia. She also assures Dawn that Caleb loves her, describing how he cried at the prospect of her death. Dawn is surprised, remembering that Caleb did not cry when Amelia died.

Natalie texts her location to Seth and Caleb. When the two men arrive, Caleb and Dawn cling to each other. Seth tells Natalie that the unidentified female body has now been identified as Tara Wilkes. Natalie realizes that Dawn murdered Tara.

Dawn

A year later, Natalie and Dawn organize the 5K charity event together. Dawn and Caleb complete the run in memory of Mia. Dawn now accepts that Caleb loves her and has moved in with him. Dawn reflects that Caleb still does not know that she murdered Tara, thanks to Natalie’s decision to keep quiet. After the events on the pier, Dawn explained her disappearance to the police by claiming that a heavy ceramic turtle fell on her head, leaving her concussed and disoriented for days.

Now, at the end of the race, Caleb produces an engagement ring and proposes. Dawn accepts and is grateful to Natalie for saving her life. The two women wave to each other.

Natalie

Natalie believes that Caleb and Dawn will be happy together, even though Caleb does not know what his fiancée is capable of. As usual, Natalie has skimmed a small proportion of the 5K’s proceeds for herself. The previous year, she was forced to transfer the money to Vixed to cover the amounts she had stolen from the company. She knew that Seth would not look too closely at the accounts.

Vixed is booming despite being forced to recall Collahealth. Seth is now divorced from his wife and committed to a relationship with Natalie. She recalls that prior to the events surrounding Dawn’s stage disappearance and apparent murder, Natalie had hoped to engineer an end to Seth’s marriage by sending Melinda an anonymous note revealing Seth’s infidelity. She also pretended that Melinda was threatening her to gain Seth’s sympathy. However, Natalie gave up on these manipulations when Seth’s wife genuinely started threatening her. Natalie is now confident that she will marry Seth and have his children.

Natalie reveals that Dawn knows about the money she embezzled from Vixed. Dawn’s discovery of the crime was the real reason that Natalie went to Dawn’s house on the day she went missing. However, Natalie now feels confident that her secret is safe with Dawn, because they are both “dangerous” women.