The movie Lies Between Friends follows a group of college friends who reunite for a bridal shower. Joss and Cait, who were once best friends, have not spoken in years since Joss found out that her fiancé had been visiting Cait on the night he died in a motorcycle accident. Cait has been trying to make amends with Joss as part of her recovery program, but before she can explain herself, she dies under mysterious circumstances.
Joss becomes suspicious of the circumstances surrounding Cait's death and begins to investigate. She discovers that Cait had been keeping some secrets from their group of friends and had been struggling with addiction and mental health issues. As Joss digs deeper, she realizes that Cait's death may not have been an accident, but rather a deliberate act by someone in their close-knit circle of friends.
As Joss gets closer to the truth, she must confront her own guilt and regrets about her relationship with Cait and the way their friendship ended. The movie explores themes of friendship, trust, addiction, and mental health, as well as the consequences of secrets and lies among friends.