A brilliant doctor and a fantastic friend, Katie is the anchor of the group. The girls' secrets are safe with Katie, but she's far less open with secrets of her own. There's one in particular she's been keeping for over two years: Kate was seeing a married patient, John, whose wife and son she's been treating for years as a family doctor. The terminally ill John asked Katie to help him end his life, and she agreed, reluctantly, to do it. At the funeral, John's son Sam reveals to Katie that he knows his father was having an affair, not realizing that Katie was the mistress. Can Katie protect her secrets, or will she lose everything, including her medical license and her freedom?

Actress Sarah Parish has had many high-profile roles on British television and film. She's best-known to American audiences for her parts in The Wedding Date and The Holiday and for portraying trophy wife Natalie Holden on BBC AMERICA's Viva Blackpool. She has also starred in The Vice, Trust, Cutting It, and the BBC's Shakespeare ReTold remake of Much Ado About Nothing. She also played the Empress of Racnoss in "The Runaway Bride" episode of Doctor Who.