Film opens at the Parliament of Life, where Swamp Thing, representing the Green, Abby Arcane, representing the Parliament of Decay, and Animal Man, representing the Red, discuss the current magical situation. Swamp Thing suddenly disappears, replaced by Floronic Man. Circe, marked by Hecate, agrees to Diana's plan to confront Hecate, who regained her powers through magical chaos. Zatanna, Bobo, and Mary search for Swamp Thing. At the Bar of Forgetfulness, Witchfire's fiery attack kills many witches, and Etrigan saves Bobo and Traci, who falls into a coma.
Diana, training at the Hall of Justice, becomes possessed by Hecate's mark and attacks Zatanna. Khalid explains the mark's significance. In the Tower of Fate, they realize Hecate is trying to control all magical locations. Diana and Etrigan stop Manitou-Dawn's control of Danny The Street. Alba, also marked, confesses to replacing Swamp Thing with Floronic Man. The team divides, with Diana, Etrigan, and Circe dealing with Hecate, and Zatanna, Bobo, and Mary searching for Swamp Thing. Diana sacrifices Manitou-Dawn to allow Diana to confront Hecate.
Diana's transformation into the Lord of Balance helps in the final battle against the Otherkind. Zatanna merges with Upside Down Man in a psychic battle. The team defeats Upside Down Man with the help of Hecate's magic. The film ends with Diana passing leadership of the Justice League Dark to Zatanna, and the team remains at the Hall of Justice, ready for new adventures.
