This episode finds the Doctor (Jodie Whittaker), Yaz (Mandip Gill) and Dan (John Bishop) in 19th century China, where a small coastal village is under threat – from both the fearsome pirate queen Madame Ching (Crystal Yu) and a monstrous alien force which she unwittingly unleashes. 　　Will the Doctor, Yaz and Dan emerge from this swashbuckling battle with the Sea Devils to save the planet?