Affinity was one of the most intriguing and excellent dramas of the entire year for me. It kept me guessing right up to the last few minutes and the evocative setting lent itself perfectly to this Victorian tale. Everything about it was gripping; the storyline with a twist was marvelous of course but also the scenery, costumes, direction and acting made this a first rate drama.

The story centred around Margaret Prior – played by Anna Madeley – who, following the death of her father, decided to volunteer as a visitor to the female inmates of Millbank, one of London’s most notorious gaols. Among Millbank’s murderers and common thieves, Margaret found herself increasingly fascinated by one inmate, the enigmatic spiritualist Selina Dawes played by Zoe Tapper.

Selina was serving time for the assault of a young girl through a malevolent spirit during a séance and despite being initially sceptical of Selina’s gifts, Margaret was sympathetic to the plight of this beautiful and seemingly innocent girl. Meanwhile, Margaret’s domineering mother was pressing her to marry, but she was repulsed by the advances of the man who saw himself as the perfect match.

Margaret found that Selina was awakening feelings in her that she’d been struggling to suppress; her physical attraction to, and love for, the prisoner grew with each visit as did her belief that Selina was truly able to interact at will with spirits.

However, Selina’s ‘spirit guide’ Peter actually turned out to be her lover – and Margaret’s maid – Ruth, who, together with Selina had a fantastic scam going that played on the Victorian’s fascination with spiritualism and, intertwined with lesbian lust, the pair preyed on vulnerable and naïve women.

Margaret was just the latest in a long line of victims but Selina so convinced her of both her love and her mediumship abilities, Margaret pledged her life and money to the girl if she could get out of prison. Selina assured Margaret that she would use the spirits to get out of the gaol and arranged a rendezvous from where the women would leave England together but the twist in the tale was that Ruth, Margaret’s maid, had stolen Margaret’s money and clothes and Selina had persuaded a prison worker to free her so the pair left together, leaving Margaret heartbroken. So much so that she felt life was no longer worth living and she threw herself off a bridge into a river.

The excellent story by Sarah Walters brought vividly to life a twilight world of séances, shadows, unruly spirits and unseemly passions. It was a powerful romantic drama as well as a fascinating look at how a spiritualism scam worked in Victorian times; it was painfully simple to execute if you had enough believers.

If you didn’t manage to watch it last night, you can catch up on itv.com and it is well worth making time to watch.