- "The great artisans say, the more a teapot is used, the more beautiful it becomes."
- ―Soo Lin Yao [src]
Soo Lin Yao was a Chinese pottery expert from Guangdong, working at the National Antiquities Museum in London. Her job was to look after a tea set and demonstrates a tea ceremony to a group of visitors.
She is first seen demonstrating the tea set to a group of visitors at the museum at the start of the episode. Whilst packing it away she explains the tea set in more detail to Andy Galbraith, another member of the staff. It is suggested that Andy has a crush on her, such as when he asks if she would like to go for a drink with him. Her response to his advances are simply to tell him to "please stop asking".
Soo Lin is seen some time later in the now darker museum where she is just finishing putting the tea set away. She hears a noise and goes to investigate where she pulls the sheet covering a statue and sees something that scares her. The next day another member of the staff, presumably Soo Lin and Andy's boss, asks Andy to go and examine a new piece the museum want to buy. He suggests that Soo Lin is more knowledgeable in that area of antiquities and is told that she quit last night. This is the confirmation that she must be somehow involved with the case that Sherlock Holmes and Dr John Watson were investigating. Sherlock discovers her involvement when he finds an unopened Yellow Pages outside her apartment, on entering the apartment he is attacked by her brother, he then realises he must find her as she may be part of the case.
Sherlock and John require Soo Lin's assistance to discover the meaning of the cipher. When they discover she is hiding in the museum from the murderer that already killed Lukis and Van Coon, she is able to tell them that all the smuggler network knows it, and that Zhi Zhu is her brother, part of the Black Lotus Tong, and that he is being controlled by a General Shan. Later, She is killed by her brother in the museum, but managed to translate two of the words in the message before her murder, Nine Mill.