Generate a question that has the following answer: The first Empress of China for the following movie plot: In year 689 of the Tang Dynasty, Wu Zetian is to be crowned the first Empress in China despite opposition from Tang officials. She has a Buddha figure built overlooking her palace in Luoyang, but an official inspecting the progress mysteriously erupts into flames. Penal officer Pei Donglai and his superior investigate and interrogate the supervising builder, Shatuo, who was formerly imprisoned after he took part in a rebellion. They find nothing and Pei's superior dies soon after erupting into flames. The Empress orders former detective and rebel Di Renjie be released from prison after the Imperial Abbot states that he must solve the mystery of the fire. She sends her attendant Shangguan Jing'er to fetch Di from prison, where they are attacked by assassins. Wu reinstates Di as the royal detective and assigns Jing'er to be both an assistant and spy. Jing'er attempts to seduce Di, but is interrupted by assassins. Di meets Prince Li, who fails to recruit him into leading a rebel army. When Pei takes Di and Jing'er to inspect the charred corpses, Di deduces the assassins use a poison that ignites upon contact with sunlight. Pei joins Di in his investigation. Di reunites with his friend Shatuo, who suspects the poison to be the venom of "fire beetles". He points Di to Donkey Wang, who is hiding in a network of caverns called the Phantom Bazaar. Pei orders Shatuo arrested for not telling him of this before, but Di stops him. At the Phantom Bazaar, Di, Pei, and Jing'er are attacked by a figure who seems to be the Imperial Abbot. After Jing'er and Pei fight him, Pei pursues him to the Abbot's forbidden residence. Donkey Wang reveals that he was the court physician and tried to use fire beetles as medicine. Finding their true danger, he disguised his appearance using acupoints and fled. Prince Li returns Di's mace to him, which was taken after he was imprisoned. Di maintains his political neutrality, and Li is assassinated soon after. Di suspects the Abbot's involvement, but Wu warns him that he will be killed if...
The answer to this question is:
Who is Wu Zetian?