Out lesbian writer Sarah Waters (Tipping the Velvet, Fingersmith) is one of the 21st century’s most brilliant novelists who does not shy away from writing sapphic romances, and her 1999 masterpiece Affinity is no exception. This beautiful, yet chilling, tale of forbidden love is set in London at the Millbank prison filled with killers and common thieves.

Needing a distraction from mourning the death of her father and controlling mother, young and gorgeous Margaret (Anna Madeley) volunteers at the prison to be a "Lady Visitor" - a stately woman who shows the female inmates proper manners. She meets, and becomes enamored, with mysterious Selina (the stunning and wide-eyed Zoe Tapper) who is incarcerated for assaulting a young girl during one of her séances. Margaret’s occasional visits increase more and more to the point where she can’t stay away from the seductive spiritualist who unlocks her naïve caller’s true feelings.

As the emotional and carnal tensions build, impassioned Margaret frantically plots for the illicit lovers to be together outside the prison walls, but not without a shockingly haunting conclusion.