The story is also another block horror – limited locations and cast. Claustrophobic, intense relationships. The situation, though initially simple, had to begin with the stakes raised for Jess, the principal character. She’s like many women out there: broke but working hard and a single parent. She’s also a victim of domestic violence and afraid of her ex-husband, who’s manipulative, persistent and controlling. She has a lovely daughter she can barely provide for who is being bullied at school. But if she can keep this gruelling and under-appreciated gig-economy job going, balancing pennies with child-minders, she can get them out of an awful situation and into a new flat. A new future. She can almost taste it. But everything is going to get so much worse and she could lose far more than her future plans. She could lose her mind, her daughter and her life . . . by taking the job she desperately needs.

Tony won’t go away and her new client is disturbed and verbally and physically abusive. The woman’s house is a half-lit minefield of horror and decay, lost in the shadow of the worst kind of tragedy any parent can face, in which something really sinister may also have happened. And let’s not forget a suggestion of the numinous. That’s just the first act. It wasn’t easy to show all of that in twenty six pages in a screenplay format. Compression: what I learned about compression in the screenplay served me well with this novel.

And so far, the book has had three very good young directors come and go onto other things, and they all made a contribution to the story. A fourth who considered the job made a startling observation in a meeting about a plot hole. The producer, Will, pitched in constantly. The first two directors wanted Tony to appear more sympathetic, and rightly too. They also had me going back at this, again and again, to get Jess on night shifts, so my daylight scenes became night-time scenes. The scene with the neighbour who imparts the house’s back story, plus enigma, nearly broke me. Izzy’s experience in the school outbuilding mirrored a place in the producer’s childhood. So, the story was collaborative – it had several editors, more or less – and for a long time after draft five, I couldn’t bear to reopen the screenplay. For a novelist with a well-developed internal editor, development within a group can be anathema. I didn’t come from a background of workshopping stories: I’ve always worked alone, or with one editor. But, you learn, you adapt. Mercifully, I’ve never closed myself off to new ways of writing or publishing. And, hey, even though I am fifty-two (at the time of writing this), I don’t think I’m too old to get into this script game either.