In the quiet American town of Salem, popular high school student Lily (Odessa Young
) spends a lot of time on her phone — texting, posting on social media, instant messaging — just like her three best friends, Em (Abra), Sarah (Suki Waterhouse
) and Bex (Hari Nef
). Lily has a boyfriend, Mark (Bill Skårsgard), but at the same time is sending sexy selfies to her next door neighbor, a married dad named Nick (Joel McHale
Their peaceful, albeit shallow lives, take a turn when someone starts hacking into the phones of the people of Salem. The mayor (Cullen Moss) is exposed for his habit of hiring male escorts. High school principal Turrell (Colman Domingo) is found to have nude photos of his six-year-old daughter in the bathtub on his phone and is accused of being a pedophile. Ordinary citizens suddenly find their text messages and photos have also been shared with everyone in town. When the activity is traced to Lily’s house, the four best friends are targeted by the citizens of Salem, who turn violent.