When this doctor writes a script, producers start feeling reel good

When your child looks sick, you take them to the doctor. Writers do the same with scripts that aren't up to scratch - except they take them to script doctors.

They're the unsung heroes of the film industry, breathing life into the work of lesser writers. Sometimes they adjust the structure, sometimes they give the dialogue more punch, and sometimes they rewrite everything. It's a lot of work for little recognition - script doctors are almost always uncredited.

Reading other people's efforts can be a tough job. But someone has to do it - and in New York that someone is quite often Marilyn Horowitz. She's spent the best part of the past decade combing through other people's writing to find the good bits, get rid of the bad bits and put what's left in order. A reader of about 200 film scripts a year, she works for individual writers, film companies - who she's not allowed to name - and also passes on her expertise to students at New York University.

'A script doctor traditionally handles rewriting, and that's a part of what I do,' Horowitz says in her office near New York's Central Park. 'For instance, a producer might have a script that's too expensive to shoot, because there are too many locations in it. It's expensive to film in a lot of different places. So he'll bring it to me and I'll collapse some of the locations together to make it affordable. Or a producer may have a script she likes, but wants to cast an actor 20 years younger than the one that's written. So I'll rewrite it with a younger character.'

Structure - which scene goes where - plays a big part in films these days, says Horowitz. 'A film might simply not be working, and that's usually because the structure isn't right. If someone comes to me with this kind of problem, I act a bit like a doctor. It's my job to heal their script.

'I have a method I've developed, and I apply this to the script and diagnose the problems. It allows me to sort out the cause of the film's problems very specifically. I can point to certain pages that need to be changed, or show the director where a new scene needs to be inserted, for instance.'