As an author I love hearing from my readers - but I never expected one to thank me for saving their mum's life.
After my debut novel was published last year, I was delighted to be contacted by people who'd enjoyed reading it. It wasn't something I'd given much thought to before being published. I'd expected reviews on Amazon, Goodreads and so on, but not this.
So the first time someone sent me an email through my website, telling me how much my book had meant to them, it felt really special.
A review is one thing. It can be positive, negative or somewhere in between. However, in my experience, those who choose to contact me directly are the ones who've really connected with my work. I'm lucky enough to have heard from readers as far away as India and Japan.
The subject matter of my first book - about a single dad who dies and remains at his young daughter's side as a spirit - seems to have struck a chord with a lot of people who've been recently bereaved.
Hearing from those who've taken comfort from my story has meant a great deal to me, validating all the hard work and knock-backs I faced en route to publication.
But nothing prepared me for the message that arrived through my Facebook page one sunny day last July.
'Just wanted to thank you for possibly saving my mother's life last week,' it began.
Talk about a way to grab my attention.
I was on a train at the time, using my mobile to catch up on my social media accounts; not expecting to come across anything out of the ordinary. Then this.
My eyes were out on stalks. My first thought was that I must have got the wrong end of the stick - but a re-read confirmed I hadn't.
It must be a wind-up, then, I told myself. I thought it had to be one of my friends having a laugh.
But, no, it wasn't anything like that. As I read on, it quickly became clear that this was a genuine message.
The reader went on to inform me that she'd just finished reading Time to Say Goodbye.
She explained that her mum had suffered a 'mini stroke' and, since this had also happened to a character in the book, she'd known what to do.
'Because of you,' she wrote, 'I recognised the seriousness of what had happened and insisted on a GP visit, which was followed by a hospital appointment.
'She is now on medication to prevent a further and larger stroke occurring. I cannot find the words to express how grateful to you I am, so a simple THANK YOU. It is definitely not the right time for me to let her go.'
Once I'd picked my jaw up off the ground, I reflected on the passage she was referring to, in which the main character's father has a transient ischaemic attack (TIA), commonly known as a 'mini stroke'.
He mistakenly brushes it off as nothing to be worried about and doesn't even tell his wife. Then, soon afterwards, he ends up suffering a full-blown stroke: something that could have been avoided if he'd immediately sought professional help.
When I was originally writing the manuscript, which had no hint of a publishing deal at that stage, I remember taking the time to research TIAs online. I visited various medical websites to make sure that all the details were right. (I used to be a newspaper journalist, so fact-checking is in my blood.)
Little did I know how important that task would end up being for this reader and her mother. I certainly made a point of replying to her message. I thanked her for telling me this amazing story, wishing her and, of course, her mother all the best for the future.
I'm so thankful I took the time to do that research. It just goes to show how important it is to get the fine details right when constructing a novel.
It might be fiction, but that's no excuse to avoid dotting the i's and crossing the t's.
Who knows? It could be the difference between life and death.
If Ever I Fall by S.D. Robertson (Avon, £7.99) was published on 9 February.