Although Thirteen feeds into the best-selling Psychic Surveys series, and is the story of sub-character, Ness, it can also be read as a standalone.

Don't leave me alone in the dark....

In 1977, Minch Point Lighthouse on Skye's most westerly tip was suddenly abandoned by the keeper and his family - no reason ever found. In the decade that followed, it became a haunt for teenagers on the hunt for thrills. Playing 13 Ghost Stories, they'd light 13 candles, blowing one out after every story told until only the darkness remained.

In 1987, following her success working on a case with Sussex Police, 25-year-old psychic Ness Patterson is asked to investigate recent happenings at the lighthouse. Local teen Ally Dunn has suffered a breakdown following time spent there and is refusing to speak to anyone. Arriving at her destination on a stormy night, Ness gets a terrifying insight into what the girl experienced.

The case growing ever more sinister, Ness realises: some games should never be played.