Who is Angela McCarthy from Dragon Bones: A Novel and what is their importance?

Angela McCarthy is the sister of the slain archaeological student, Brian. She traveled to China after her brother sent her a photograph of small mushrooms, which indicated the presence of a huge fungus growing under the surface. Angela, as a mycologist, was highly interested in his discovery, so she came immediately to the area, only to find her brother had disappeared, and later, she learns he had been killed. Angela lies to Hulan and to David several times in an effort to keep her brother's finding a secret, but her lies are not malevolent. She is not a bad character, merely a sister who loved her brother and wanted to help him and preserve his memory.