By 1807, Zheng Yi Sao had begun to make a name for herself by commanding her own ship and crew. She also had two sons, a three-year old and a six-year old, amongst her crew. They, along with the rest of Zheng's crew, were taken hostage and ransomed by Guo Podai and his Black Flag Fleet. Zheng promised him that she would return to them with the lost treasure of the Flor de la Mar, and set sail on her own. Seeking information about the whereabouts of the ship, she destroyed a statue in which a piratical Sea Devil was imprisoned. Ying Wai attempted to stop her, but was killed by the Sea Devil instead.
She subsequently left aboard her ship to find the shipwreck containing the treasure, which Dan Lewis and Wai's son Ying Ki stowed away on. Upon discovering the two, she pressed them into her service. The three then discovered that they could no longer navigate; their compass no longer pointed north, and the position of the stars in the sky continually shifted. The ship was then discovered and attacked by the sea monster Hua-Shen, whom Zheng initially dismissed as "just a myth". She ordered a cannon bombardment, but Hua-Shen deflected the cannonballs, which exploded.
After escaping from Hua-Shen, Ji-Hun's ship emerged from underwater next to Zheng's, carrying the Thirteenth Doctor, Yasmin Khan, and Sin Ji-Hun, as well as several Sea Devils. After the Chief Sea Devil discovered the Keystone was worn by Ying Ki as a necklace, Zheng proceeded to fight alongside the Doctor, Yaz, Dan, Ji-Hun, and Wai for possession of it. The fight ended with the Doctor and Ji-Hun successfully trapping the Sea Devils underwater using the Keystone.
Following the fight, and with Ji-Hun's permission, Zheng offloaded the treasure of the Flor de la Mar from Ji-Hun's ship onto her own. She noted that it was enough to return her crew to her. Claiming him as her responsibility, she invited Wai to join her crew, and subsequently rebuked him when he hugged her. (TV: Legend of the Sea Devils)