Published in 2022, Sue Lynn Tan’s Heart of the Sun Warrior is the second and final book in the Celestial Kingdom duology. The novel concludes the story of Xingyin, daughter of the moon goddess, Chang’e, which began in Daughter of the Moon Goddess (2022). After winning her mother’s freedom, Xingyin faces a new threat from within the Celestial Kingdom. A shocking revelation about her family’s past forces the protagonist to confront a new tyrannical enemy, compelling her to fight for her loved ones and the fate of the immortal and mortal realms. The novel explores themes such as The Conflict Between Duty and Personal Integrity, Vengeance as a Path to Tyranny, and Sacrifice as the True Measure of Love.

Author Sue Lynn Tan was born in Malaysia and developed a love for mythology and folklore as a child. The Celestial Kingdom duology fits within the popular xianxia genre—Chinese fantasy which features worlds of gods, demons, and immortals. The novels are a modern reimagining of the classic Chinese myth of Chang’e and Houyi. A national bestseller, Daughter of the Moon Goddess won a 2023 Alex Award. Heart of the Sun Warrior was also a national bestseller. 

This guide refers to the 2023 Harper Voyager Paperback edition.

Content Warning: The source text and this guide contain descriptions of graphic violence, animal cruelty, illness and death.

Plot Summary

The novel begins a year after Xingyin won her mother, Chang’e’s, freedom. Xingyin lives peacefully on the moon at the Pure Light Palace with Chang’e and their attendant, Ping’er. She rekindles her romance with Crown Prince Liwei of the Celestial Kingdom. Xingyin’s friend from the Celestial Kingdom’s army, Shuxiao, also visits, describing the harsh new military regime under General Wu.

An elderly musician named Master Gang and a winemaker named Haoran arrive at the palace. Late one night, Xingyin discovers Master Gang attempting to chop down the everlasting laurel tree. They fight, and Master Gang injures Ping’er before escaping. Xingyin heals Ping’er’s neck wound and discovers that a fallen seed from the moon laurel tree possesses regenerative magic. The tree has been healing Xingyin’s lifeforce since her return from battle.

Haoran confesses that his wine was drugged and meant to incapacitate them. He also reveals that Master Gang wore a jade ornament symbolizing the Celestial Kingdom. Later, Liwei declares his intention to marry Xingyin, despite his parents’ disapproval. Prince Wenzhi of the Demon Realm also visits, warning that General Wu has a particular interest in Xingyin.

Xingyin accepts Liwei’s invitation to his father’s birthday banquet. At the Celestial Emperor’s gathering, Xingyin discovers that General Wu is Master Gang, and was once a mortal named Wugang. Wugang was sentenced to chop down the self-healing moon laurel as punishment for murdering his unfaithful wife and her immortal lover. He succeeded by using his own blood to halt the tree’s restoration and was rewarded with immortality.

During the banquet, the moon fails to rise, an event seen as a grave insult from Chang’e. Wugang accuses Xingyin and her mother of treason. The Emperor commands Liwei to denounce Xingyin, but Liwei refuses and publicly defies his father, leaving the banquet with her.

Returning to the moon, they find Chang’e missing. Xingyin finds her mother in the Mortal Realm, wandering near her husband Houyi's grave. After sending her mother home, Xingyin encounters an archer who reveals himself to be her father. Houyi explains he was an immortal Dragon Lord tricked by the Celestial Emperor into becoming mortal to slay the sunbirds. He is dying, and Xingyin vows to find the Elixir of Immortality to save him.

Xingyin seeks help from the Keeper of Mortal Fates’s apprentice, Leiying, and her brother, Tao. Xingyin and Tao sneak into the Imperial Treasury, fight enchanted dragonfly guardians, and steal the elixir. After they escape, Tao betrays Xingyin, vanishing with the elixir.

Shuxiao and General Jianyun arrive to warn Xingyin that Wugang is coming with an army to imprison them. The attack is the Emperor’s punishment for Chang’e’s failure to light the moon, which was caused by a note Wugang sent to lure her away. As Xingyin, Chang’e, Ping’er, and Shuxiao plan to flee, Wugang’s army arrives and sets the Pure Light Palace on fire. Wugang captures Chang’e and Ping’er. During the confrontation, Chang’e’s blood spills on the laurel, causing thousands of seeds to fall. In the ensuing struggle, Wugang strikes Ping’er. Wenzhi arrives and helps them escape, but Ping’er dies, her last wish being to return to her home in the Southern Sea.

Grieving, the group travels to the Southern Sea with Ping’er’s body. Using a magical pearl Ping’er gave her, Xingyin opens a passage to the underwater kingdom, where they are brought before Queen Suihe. Wenzhi visits and warns them of Queen Suihe’s fickle nature, also informing them that Liwei is being held under guard. Desperate, Xingyin decides to ask the Celestial Empress for help.

Xingyin meets the Empress in a mortal teahouse. The Empress reveals Wugang is plotting to usurp Liwei’s position as heir. She agrees to help free Liwei only if Xingyin swears to end her relationship with him forever. Xingyin agrees but forces the Empress to swear not to harm her or her family and to capture the thief, Tao.

Using enchanted shells to create musical decoys, Xingyin infiltrates the Jade Palace. She meets Liwei’s long-lost half-sister, who left the Celestial Kingdom to marry a mortal.  Zhiyi helps Xingyin subdue the guards, and they free both Liwei and Tao. Zhiyi gives the stolen elixir to Xingyin, despite wanting it to heal her husband. True to her vow, Xingyin breaks up with a heartbroken Liwei, claiming she still has feelings for Wenzhi.

Xingyin gives the elixir to Houyi, who is restored to his immortal form. She takes her father to the Southern Sea, where he and Chang’e reunite. Their reunion is cut short when Queen Suihe summons them to meet Prince Yanxi and his younger brother, Prince Yanming, of the Eastern Sea. A messenger arrives from Wugang, who has seized control of the Celestial court, and Queen Suihe betrays Xingyin’s group. They escape only to be ambushed on the beach by Wugang and his army of resurrected, undead Celestial soldiers animated by laurel seeds. In the chaos, Prince Yanming sacrifices his life to save his brother.

Xingyin summons the Four Dragons, and Wenzhi captures Wugang. However, Wugang threatens to unleash his full army across all realms if he is harmed. The group agrees to release Wugang in exchange for a week’s truce. Xingyin deduces that the laurel seeds were created from the combination of Chang’e’s tears and Wugang’s blood. The Long Dragon reveals that the only way to destroy the laurel is with the Sacred Flame Feather from the last sunbird, which resides with its mother, the Sun Goddess, Lady Xihe.

The group travels to the Fragrant Mulberry Grove. During a confrontation, the Celestial Empress attacks Xingyin, breaking their pact. Xingyin realizes she is now free from her vow to give up Liwei. She enters the grove alone and confronts Lady Xihe. Xihe challenges Xingyin to defeat her fire phoenix without using magic. Xingyin succeeds in taming the phoenix without killing it. Moved by her actions, the last sunbird offers its Sacred Flame Feather. Wenzhi comforts the exhausted Xingyin, and they share a kiss just as Liwei arrives.

To get close to the laurel, the group determines they need a magical disguise. Wenzhi reveals that his father, King Wenming, possesses the Divine Mirror Scroll. King Wenming agrees to help only if Xingyin marries Wenzhi to forge an alliance. They plan a fake wedding, but during the ceremony, Wenzhi’s brother, Prince Wenshuang, launches a coup and fatally wounds the king, revealing his own alliance with Wugang. In the ensuing battle, Xingyin kills Wenshuang to save Wenzhi. The dying king names Wenzhi his heir and gives him the scroll.

Wenzhi becomes the new king and uses the scroll to disguise Xingyin as her mother. The spell creates a magical link that binds Xingyin and Wenzhi. Xingyin hides the feather within her own lifeforce. Wugang’s soldiers capture her and bind her to the laurel tree. Realizing she must sacrifice herself, Xingyin unleashes the feather’s full power. The energy destroys the laurel and Wugang’s undead army. As Wugang prepares to kill the dying Xingyin, Houyi fatally strikes him with Sky-fire arrows. The magical link from the spell kills Wenzhi, as he sacrifices his lifeforce to protect Xingyin. As Xingyin confesses her love for him, she dies as well. Chang’e’s tears fall on the laurel’s stump, activating its last trace of power to resurrect Xingyin.

In the aftermath, Liwei becomes the new Celestial Emperor. Grieving, Xingyin tells Liwei she cannot marry him, and they part as friends. She returns to the moon to live with her parents. Years pass as Xingyin slowly heals, frequently visiting the border of the Cloud Wall, where she can sense a remnant of Wenzhi’s spirit. One day, the presence vanishes. Xingyin goes to Emperor Liwei, who reveals that the laurel’s magic saved Wenzhi’s spirit. They nurtured it until it was strong enough to be reborn as a mortal, a process that will preserve his immortal self for his eventual return. Liwei offers Xingyin the next Elixir of Immortality, but she asks him to give it to his half-sister first. Xingyin travels to the Mortal Realm and finds Wenzhi, now a mortal minister who does not remember her but feels an instant connection. He asks to see her again, and she agrees, ready to start anew.