In 2012, teens Michelle Carter and Conrad Roy fell in love; even though they lived hours apart and met in person no more than five times, they exchanged thousands of texts over a two-year period. Then on July 13, 2014, 18-year-old Conrad was found dead in his car in a parking lot. What appeared to be a standard case of suicide by carbon-monoxide intoxication took a shocking turn when investigators discovered alarming text messages in which Michelle, 17, relentlessly encouraged Conrad to kill himself, even after Conrad had second thoughts and removed himself from his car. Michelle was arrested for involuntary manslaughter, sparking a controversial case that grabbed national attention. Though the Roy family admits Conrad suffered from depression, they maintain that he was doing well before his death and lay the blame solely in Michelle's hands. As the trial begins in June 2017, with Michelle waiving her right to a jury, the prosecution paints a picture of Michelle as a lonely and needy girl who orchestrated her boyfriend's death to get attention from a group of girls at her school.

In an attempt to prove that she was not solely responsible for boyfriend Conrad Roy's suicide, Michelle Carter's legal team begins their defense by focusing on Conrad's relationship with his parents. They next call to the stand clinical psychiatrist Dr. Peter Breggin as an expert witness to speak to Michelle's own mental-health issues and her prescribed medications that may have influenced her perception of reality. A deeper dive into texts between the teenagers reveals a more complicated relationship than meets the eye; the defense argues that Michelle took Conrad's lead when encouraging his suicide and looked to pop culture for inspiration in building up a fantasy around her troubled romance. As the surrounding community remains split on whether Michelle is a murderer or a victim, the judge reaches a verdict in a complex case that could have significant legal consequences.