Malta, daughter of fire goddess Themis and heir to the Fire Kingdom, must guard the Holy Flame nightly until her sixteenth birthday, when she will ascend as queen. This flame maintains calm seas and grants eternal life to fire beings. Her duty reflects her royal lineage and the ancient fire-water conflict, stemming from a betrayal by wind god Argon that divided her mother and sea god Glaucus.

Malta first meets sea prince Sirius when he enters forbidden waters near her flame. Wary due to deep prejudice against water beings, she overcomes suspicion after their second encounter. Sharing stories bonds them, sparking mutual affection. Their romance defies the elemental divide enforced by their parents, challenging generations of enmity.

Facing separation as her coronation nears, Malta attempts suicide by leaping into the Holy Flame. Sirius rescues her, and their survival—shielded by love—reveals their unique compatibility. An elder sea turtle later tells them of a legendary star where fire and water coexist, reachable via spores from Klaesco blossoms blooming during an eclipse. This discovery fuels their resolve to unite.

Neglecting the Holy Flame to escape with Sirius causes it to extinguish, threatening her people. Her friend Piale sacrifices herself to reignite the flame, delaying pursuit. Malta and Sirius are captured by their parents and imprisoned for betrayal. After sprites help them escape, Malta journeys to Mobius Hill for the blossoms but fails to secure spores before transforming into the Fire Queen during the eclipse. Her new status hardens her; she coldly rejects Sirius upon his arrival, unaware he was delayed battling Argon.

Blinded from a fall yet undeterred by daylight, Sirius reaches her as the eclipse ends. Sunlight kills him. Malta carries his body into the sea, reverts to her original form, and dies beside him. Their deaths reconcile their parents, who send their spirits to the heavens to create a world where fire and water coexist as one.