After moving to Element City, fire elements Bernie and Cinder Lumen (voices of Ronnie del Carmen and Shila Ommi) have a daughter, Ember (Leah Lewis) and run a shop called the Fireplace, which Bernie hopes to pass to Ember when he retires. She struggles to control her temper and, one day, accidentally breaks a water pipe and floods the Fireplace's basement, which brings Wade Ripple (Mamoudou Athie), a water element and city inspector, into her life.

As Wade falls in love with Ember, can he prove to her that fire and water can mix after all and, in so doing, win her heart?