Parallel follows the story of Vanessa (Danielle Deadwyler) who takes refuge at her family's lake house to grieve after suffering the loss of her child. Accompanied by her husband, Alex (Aldis Hodge), and his brother, Martel (Edwin Hodge), Vanessa attempts to regain her sense of normalcy after the tragedy. But soon after their arrival, she experiences an aberration when she is attacked by a parallel universe's version of herself. Faced with the reality that multiverses exist, she must reconcile the fact that these parallel gates will either hold the key to releasing her grief or trapping her forever.